Health Education Systems Inc (HESI) A2 Exam Quiz: Decimal Operations
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Decimal OperationsQuestion 1 of 20

A nurse administers a total of 18.75 mg of a pain medication to a patient over 5 equal doses. How many milligrams were in each individual dose?

3.25 mg
3.75 mg
4.25 mg
93.75 mg
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Health Education Systems Inc (HESI) A2 Exam Quiz

Health Education Systems Inc (HESI) A2 Exam Quiz: Decimal Operations

Practice Decimal Operations in Health Education Systems Inc (HESI) A2 Exam with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Decimal Operations, giving you a quick way to practice the rules, question types, and explanations that matter most for Health Education Systems Inc (HESI) A2 Exam.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A nurse administers a total of 18.75 mg of a pain medication to a patient over 5 equal doses. How many milligrams were in each individual dose?

  1. 3.25 mg
  2. 3.75 mg (correct answer)
  3. 4.25 mg
  4. 93.75 mg
Explanation: When you encounter medication dosage problems, you're working with basic division to find equal parts of a total amount. This type of calculation is fundamental in nursing practice for ensuring accurate medication administration. To find the amount in each individual dose, you need to divide the total medication given by the number of equal doses: 18.75 mg5 doses=3.75 mg per dose\frac{18.75 \text{ mg}}{5 \text{ doses}} = 3.75 \text{ mg per dose}. This confirms that answer choice B (3.75 mg) is correct. Let's examine why the other options are incorrect. Choice A (3.25 mg) would result if you made an arithmetic error during division or perhaps confused this with a similar problem. If you multiply 3.25 × 5, you get 16.25 mg, which is less than the total given. Choice C (4.25 mg) is another calculation error—multiplying 4.25 × 5 gives you 21.25 mg, which exceeds the total medication administered. Choice D (93.75 mg) represents a fundamental conceptual error where you might have multiplied instead of divided (18.75 × 5 = 93.75), which would give you five times the total dose rather than one-fifth of it. For HESI math problems involving medication dosages, always double-check your answer by working backwards. Multiply your calculated dose by the number of administrations to verify it equals the original total. This reverse-calculation strategy will catch most arithmetic errors and help ensure patient safety in real-world applications.

Question 2

A medication order directs a patient to take 1.5 tablets twice a day. The patient follows this regimen for 3.5 days. How many tablets has the patient taken in total over this period?

  1. 7.0
  2. 10.5 (correct answer)
  3. 11.5
  4. 21.0
Explanation: Medication dosage calculations require careful attention to both the frequency and duration of treatment. When you encounter problems involving partial days or fractional doses, break down the calculation into clear steps to avoid common errors. To solve this problem, first identify what the patient takes per day: 1.5 tablets twice daily equals 1.5×2=3.01.5 \times 2 = 3.0 tablets per day. Next, multiply by the duration: 3.0 tablets/day×3.5 days=10.53.0 \text{ tablets/day} \times 3.5 \text{ days} = 10.5 tablets total. Looking at the wrong answers: Choice A (7.0) represents a common error where someone might have calculated 1.5 tablets × 2 doses × 2 days, incorrectly rounding 3.5 days down to just 2 full days. Choice C (11.5) could result from miscalculating the daily dose as 3.5 tablets instead of 3.0, then multiplying by 3.5 days. Choice D (21.0) appears to double the correct answer, possibly from counting each 1.5-tablet dose separately (1.5 × 2 × 3.5 × 2) or making another multiplication error. The key strategy for HESI dosage calculations is to always work systematically: calculate the total daily dose first, then multiply by the number of days. Don't rush through fractional numbers—double-check your arithmetic, especially when dealing with decimals. Remember that 3.5 days means the full regimen for 3 complete days plus half of the fourth day's doses.

Question 3

A nurse is tracking a patient's fluid intake during a 12-hour shift. The patient consumed 0.24 L of water, 0.12 L of juice, and received 0.45 L of intravenous fluids. What is the patient's total fluid intake in liters for the shift?

  1. 0.71 L
  2. 0.81 L (correct answer)
  3. 8.1 L
  4. 81.0 L
Explanation: When you encounter fluid intake calculations on the HESI, you're being tested on your ability to accurately track and sum all fluid sources - a critical nursing skill for monitoring patient hydration status and kidney function. To find the total fluid intake, you need to add all three fluid sources together. Since all measurements are already in liters, you can add them directly: 0.24 L+0.12 L+0.45 L=0.81 L0.24 \text{ L} + 0.12 \text{ L} + 0.45 \text{ L} = 0.81 \text{ L} Let's work through this step by step: 0.24 + 0.12 = 0.36, then 0.36 + 0.45 = 0.81 liters total. Looking at the incorrect options: Choice A (0.71 L) likely results from a simple addition error, perhaps miscalculating 0.24 + 0.12 as 0.14 instead of 0.36. Choice C (8.1 L) represents a decimal place error - moving the decimal point one place to the right, which would indicate a fundamental misunderstanding of decimal arithmetic. Choice D (81.0 L) shows an even more severe decimal error, moving two decimal places, which would represent an impossibly large fluid intake (over 21 gallons). Always double-check your decimal alignment when adding numbers with decimals, especially under exam pressure. Line up the decimal points vertically and add column by column. Remember that accurate intake and output documentation is essential for patient safety - a calculation error could lead to missing signs of fluid overload or dehydration.

Question 4

A 1-liter (1000 mL) bag of normal saline is infusing for a patient. After several hours, the nurse checks the bag and notes that 455.5 mL have been administered. How many milliliters of saline remain in the bag?

  1. 455.5 mL
  2. 544.5 mL (correct answer)
  3. 545.5 mL
  4. 555.5 mL
Explanation: This is a straightforward subtraction problem that tests your ability to perform basic calculations accurately under testing conditions—a critical skill for medication administration and fluid balance monitoring in nursing practice. To find how much saline remains, you need to subtract the amount already administered from the original total: 1000 mL−455.5 mL=544.5 mL1000 \text{ mL} - 455.5 \text{ mL} = 544.5 \text{ mL}. This means 544.5 mL of saline remain in the bag, making answer B correct. Let's examine why the other options are wrong. Answer A (455.5 mL) simply restates the amount already given—this represents a misreading of what the question asks. Answer C (545.5 mL) results from a calculation error, likely adding 1 mL somewhere in the process or misaligning decimal places. Answer D (555.5 mL) suggests a more significant calculation mistake, possibly subtracting incorrectly or confusing the numbers entirely. For HESI success, always double-check your arithmetic, especially with decimal calculations involving IV fluids and medications. Set up the problem clearly: Total - Used = Remaining. These seemingly simple math questions can trip you up under test pressure, so practice mental math regularly and verify your work. When dealing with IV calculations on the exam, remember that precision matters—small errors in fluid calculations can have serious clinical consequences, so the HESI expects perfect accuracy on these foundational skills.

Question 5

A patient is prescribed a medication that comes in 2.5 mg tablets. The prescription directs the patient to take 1.5 tablets every morning. What is the total dosage in milligrams (mg) that the patient receives each morning?

  1. 3.75 mg (correct answer)
  2. 4.00 mg
  3. 37.5 mg
  4. 40.0 mg
Explanation: Medication dosage calculations are fundamental nursing skills that require careful attention to detail and systematic problem-solving. When you encounter questions involving partial tablets, break the calculation into clear steps to avoid errors. To find the total morning dosage, you need to multiply the strength of each tablet by the number of tablets prescribed: 2.5 mg/tablet×1.5 tablets=3.75 mg2.5 \text{ mg/tablet} \times 1.5 \text{ tablets} = 3.75 \text{ mg} You can also think of this as: one full tablet (2.5 mg) plus half a tablet (1.25 mg) equals 3.75 mg total. Answer A (3.75 mg) is correct because it represents the accurate multiplication of tablet strength by quantity prescribed. Answer B (4.00 mg) likely results from rounding 3.75 up to 4, but medication calculations require exact precision—never round unless specifically instructed. Answer C (37.5 mg) suggests a decimal place error, possibly from incorrectly calculating 25 × 1.5 instead of 2.5 × 1.5. This is a dangerous ten-fold overdose error. Answer D (40.0 mg) represents an even larger calculation error, possibly from misreading the tablet strength as 25 mg or making multiple computational mistakes. For HESI success, always double-check your decimal placement in dosage calculations, as medication errors can be life-threatening. Set up your calculation clearly, perform the math step-by-step, and verify that your answer makes logical sense given the original tablet strength. Remember that taking 1.5 tablets should give you more than one tablet's worth but less than two tablets' worth of medication.

Question 6

A pharmacy technician must divide a stock solution of 22.5 mL into smaller vials, with each vial containing exactly 0.75 mL. How many full vials can be prepared from the stock solution?

  1. 3
  2. 16
  3. 30 (correct answer)
  4. 300
Explanation: This problem tests your ability to perform basic division calculations that are essential in pharmacy practice, where precise dosing and medication preparation are critical for patient safety. To find how many full vials you can prepare, you need to divide the total stock solution volume by the volume per vial: 22.5 mL÷0.75 mL per vial=30 vials22.5 \text{ mL} ÷ 0.75 \text{ mL per vial} = 30 \text{ vials}. You can verify this by multiplying back: 30×0.75=22.5 mL30 × 0.75 = 22.5 \text{ mL}, which matches your original stock volume perfectly. Let's examine why the other answers are incorrect. Answer A (3) suggests you might have confused the calculation entirely, perhaps dividing 0.75 by 22.5 instead of the reverse. Answer B (16) could result from incorrectly converting the decimal—if you mistakenly treated 0.75 as 0.075, you'd get approximately 16. Answer D (300) represents a decimal placement error, likely from multiplying instead of dividing or mishandling the decimal point during division. When tackling pharmacy calculation problems on the HESI, always set up your division as "total amount ÷ amount per unit = number of units." Double-check your work by multiplying your answer back—if you get the original total, you're correct. Also, use estimation to catch obvious errors: since 0.75 is close to 1, you should expect an answer close to 22.5, making 30 reasonable while 300 or 3 should immediately seem wrong.

Question 7

A medication is dosed at 0.75 mg/kg. The patient weighs 160 pounds. Given that 1 kg is approximately 2.2 pounds, what dose should the patient receive? Round the answer to the nearest tenth of a milligram.

  1. 54.5 mg (correct answer)
  2. 54.8 mg
  3. 120.0 mg
  4. 264.0 mg
Explanation: Dosage calculations based on body weight are fundamental in nursing practice, requiring you to convert between measurement systems and apply mathematical precision. When you encounter weight-based dosing problems, always work systematically through the unit conversions first. To solve this problem, you need to convert the patient's weight from pounds to kilograms, then multiply by the prescribed dose per kilogram. Start with the conversion: 160 pounds2.2 pounds/kg=72.727 kg\frac{160 \text{ pounds}}{2.2 \text{ pounds/kg}} = 72.727 \text{ kg}. Next, calculate the total dose: 72.727 kg×0.75 mg/kg=54.545 mg72.727 \text{ kg} \times 0.75 \text{ mg/kg} = 54.545 \text{ mg}. Rounded to the nearest tenth, this gives you 54.5 mg. Looking at the wrong answers: Choice B (54.8 mg) likely results from rounding errors during intermediate steps rather than at the final answer. Choice C (120.0 mg) comes from incorrectly multiplying 160 × 0.75 without converting pounds to kilograms first—a common trap. Choice D (264.0 mg) appears to result from multiplying the unconverted weight by an incorrect factor, possibly confusing the conversion ratio. The correct answer is A (54.5 mg), which follows the proper sequence of conversions and rounding. For HESI success, always convert weights to kilograms before calculating medication doses, and remember that most dosing errors stem from skipping the unit conversion step. Practice these calculations until the pound-to-kilogram conversion (dividing by 2.2) becomes automatic, and always round only your final answer, not intermediate calculations.

Question 8

A topical cream contains 0.05% of an active ingredient by weight. How many grams of the active ingredient are in a 30-gram tube of the cream?

  1. 0.015 g (correct answer)
  2. 0.15 g
  3. 1.5 g
  4. 15.0 g
Explanation: When you encounter percentage concentration problems in healthcare, you're working with parts per hundred. A 0.05% concentration means 0.05 grams of active ingredient per 100 grams of total cream. To find the amount of active ingredient in any size tube, convert the percentage to a decimal and multiply by the total weight. Convert 0.05% to decimal form: 0.05%=0.05100=0.00050.05\% = \frac{0.05}{100} = 0.0005 Now multiply by the tube size: 30 grams×0.0005=0.015 grams30 \text{ grams} \times 0.0005 = 0.015 \text{ grams} You can also think of this as a proportion: if 100 grams contains 0.05 grams of active ingredient, then 30 grams contains 0.05×30100=0.015\frac{0.05 \times 30}{100} = 0.015 grams. Looking at the wrong answers: Choice B (0.15 g) results from forgetting to convert the percentage to decimal form—multiplying 30 by 0.05 directly instead of 0.0005. Choice C (1.5 g) comes from treating 0.05% as if it were 5%, essentially moving the decimal point incorrectly. Choice D (15.0 g) would mean the active ingredient weighs half as much as the entire tube, which is impossible since it's only 0.05% of the total. The correct answer is A (0.015 g). Study tip: Always convert percentages to decimals before multiplying, and do a quick reasonableness check—your answer should be much smaller than the total weight when dealing with small percentages like those common in medications.

Question 9

A patient's diet plan requires them to drink 8 glasses of water, with each glass holding 0.24 L. The patient has already consumed 1.5 L today. How many more liters of water must the patient drink to meet their daily goal?

  1. 0.42 L (correct answer)
  2. 1.92 L
  3. 3.42 L
  4. 6.50 L
Explanation: When you encounter dosage and fluid intake calculations on the HESI, you're working with unit conversions and basic arithmetic - skills essential for safe nursing practice. To solve this problem, start by calculating the total water requirement. The patient needs 8 glasses at 0.24 L each: 8×0.24=1.92 L8 \times 0.24 = 1.92 \text{ L} total daily goal. Since the patient has already consumed 1.5 L, subtract this from the total requirement: 1.92−1.5=0.42 L1.92 - 1.5 = 0.42 \text{ L} remaining. Looking at the answer choices: A) 0.42 L is correct - this represents the remaining amount needed after subtracting what's already been consumed. B) 1.92 L is the trap of giving the total daily requirement without accounting for what's already been consumed. This is a common error when students calculate correctly but forget to complete the second step. C) 3.42 L likely results from adding the consumed amount to the total requirement (1.92 + 1.5), which makes no logical sense for remaining intake. D) 6.50 L might come from miscalculating the total requirement or confusing the numbers entirely. The key strategy for fluid calculation questions is to break them into clear steps: calculate total requirement, identify what's already completed, then find the difference. Always double-check that your final answer makes sense - if a patient needs less than 2 L total, they certainly shouldn't need over 3 L remaining. These multi-step problems are common on the HESI, so practice working methodically through each component.

Question 10

A patient's weight was recorded as 75.4 kg on Monday. On Wednesday, the patient's weight was 73.8 kg. By Friday, the patient had gained 0.7 kg from their Wednesday weight. What was the patient's net change in weight from Monday to Friday?

  1. A decrease of 0.9 kg (correct answer)
  2. A decrease of 1.6 kg
  3. An increase of 0.7 kg
  4. An increase of 2.3 kg
Explanation: When you encounter weight change problems in healthcare, you need to track the patient's weight through each measurement and calculate the total difference from start to finish. Let's follow this patient's weight journey step by step. Starting weight on Monday was 75.4 kg. On Wednesday, the weight dropped to 73.8 kg. By Friday, the patient gained 0.7 kg from the Wednesday weight, making Friday's weight: 73.8+0.7=74.5 kg73.8 + 0.7 = 74.5 \text{ kg} To find the net change from Monday to Friday, subtract the starting weight from the final weight: 74.5−75.4=−0.9 kg74.5 - 75.4 = -0.9 \text{ kg} The negative result indicates a decrease of 0.9 kg, making A correct. Let's examine why the other options are wrong. Option B (-1.6 kg) represents the change from Monday to Wednesday only (73.8−75.4=−1.673.8 - 75.4 = -1.6), but ignores Friday's weight gain. Option C (+0.7 kg) only considers the change from Wednesday to Friday, completely missing the initial weight loss. Option D (+2.3 kg) appears to incorrectly add all the weight changes together rather than tracking the actual progression. Study tip for HESI: Weight change problems require you to follow the complete timeline from start to finish. Don't get distracted by intermediate changes—always calculate the difference between the final weight and the initial weight. Watch for distractors that represent partial calculations or mathematical errors with the intermediate steps.

Question 11

A pharmacist is comparing the cost of two brands of a vitamin. Brand A costs $18.90 for a bottle of 60 tablets. Brand B costs $24.50 for a bottle of 100 tablets. What is the difference in cost per tablet between the two brands?

  1. $0.07 (correct answer)
  2. $0.56
  3. $0.70
  4. $5.60
Explanation: When you encounter unit cost comparison problems, you need to find the cost per unit for each option, then calculate the difference between them. To find the cost per tablet for each brand, divide the total cost by the number of tablets. For Brand A: $18.9060 tablets=$0.315\frac{\$18.90}{60 \text{ tablets}} = \$0.315 per tablet. For Brand B: $24.50100 tablets=$0.245\frac{\$24.50}{100 \text{ tablets}} = \$0.245 per tablet. The difference in cost per tablet is: $0.315−$0.245=$0.070\$0.315 - \$0.245 = \$0.070, which rounds to $0.07. Looking at the answer choices: A) $0.07 is correct—this represents the actual difference in cost per tablet. B) $0.56 might result from incorrect division or using the wrong numbers in your calculation. C) $0.70 is exactly ten times the correct answer, suggesting you may have made a decimal place error in your final subtraction. D) 5.60appearstocomefromsubtractingthetotalcosts(5.60 appears to come from subtracting the total costs (24.50 - $18.90 = $5.60) rather than finding the per-unit difference. The key strategy here is to always convert to the same unit of measurement before making comparisons. Don't be tempted by answer choices that use the original numbers from the problem—these are often traps. Always double-check your decimal placement, especially when working with money, since small errors can lead you to distractor answers that are multiples of the correct response.

Question 12

A pediatric patient weighs 8.5 kg. A physician orders an antibiotic at a dosage of 15 mg per kg per day. What is the total daily dose for this patient in milligrams (mg)?

  1. 23.5 mg
  2. 120.0 mg
  3. 127.5 mg (correct answer)
  4. 135.0 mg
Explanation: Pediatric dosage calculations are fundamental in nursing practice because children's medication doses are almost always weight-based rather than standardized. When you encounter these problems, you're applying a simple multiplication formula: prescribed dose per kg × patient's weight in kg = total daily dose. Let's work through this calculation step by step. The patient weighs 8.5 kg, and the antibiotic is ordered at 15 mg per kg per day. To find the total daily dose, multiply: 8.5 kg×15 mg/kg=127.5 mg8.5 \text{ kg} × 15 \text{ mg/kg} = 127.5 \text{ mg} Now let's examine why the other options are incorrect. Option A (23.5 mg) appears to result from subtracting instead of multiplying (15 - 8.5 = 6.5, though even that doesn't quite match). Option B (120.0 mg) suggests someone rounded 8.5 kg down to 8 kg before calculating (8 × 15 = 120). Option D (135.0 mg) likely comes from rounding 8.5 kg up to 9 kg (9 × 15 = 135). These represent common calculation errors where students either use the wrong operation or round prematurely. The correct answer is C (127.5 mg). For HESI success with dosage calculations, always use the exact weights given—don't round until your final answer if rounding is specifically requested. Double-check that you're multiplying, not adding or subtracting. Practice setting up the equation so the units cancel properly (kg cancels out, leaving only mg), which helps catch setup errors before you calculate.

Question 13

A patient is advised to walk 2.5 miles each day. If the patient has already walked 0.75 miles in the morning and 0.5 miles in the afternoon, how many more miles must the patient walk to meet the daily goal?

  1. 1.25 miles (correct answer)
  2. 1.50 miles
  3. 1.75 miles
  4. 2.00 miles
Explanation: When you encounter word problems involving distances, times, or quantities on the HESI, break them down into clear steps: identify what you have, what you need, and what's missing. Here, you need to find how much more the patient must walk to reach their daily goal. Start by adding up what they've already walked: 0.75+0.5=1.250.75 + 0.5 = 1.25 miles. Then subtract this total from the daily goal: 2.5−1.25=1.252.5 - 1.25 = 1.25 miles remaining. Looking at the wrong answers: Choice B (1.50 miles) might result from incorrectly subtracting only one of the distances walked (like 2.5−1.0=1.52.5 - 1.0 = 1.5) instead of accounting for both morning and afternoon walks. Choice C (1.75 miles) could come from subtracting just the morning walk (2.5−0.75=1.752.5 - 0.75 = 1.75) and forgetting about the afternoon distance. Choice D (2.00 miles) might occur if you subtracted only the afternoon walk (2.5−0.5=2.02.5 - 0.5 = 2.0) or made an arithmetic error when combining the distances already walked. The correct answer is A (1.25 miles) because the patient has walked a total of 1.25 miles and needs 1.25 more miles to reach the 2.5-mile goal. Study tip: In multi-step word problems, always double-check that you've accounted for all given information. Write out each step clearly: total goal minus total completed equals amount remaining. This systematic approach prevents common errors like missing parts of the given data.

Question 14

A nurse needs to administer 1.2 mg of a medication. The medication is supplied in a solution with a concentration of 0.8 mg per mL. How many milliliters (mL) of the solution should the nurse administer?

  1. 0.96 mL
  2. 1.20 mL
  3. 1.50 mL (correct answer)
  4. 2.00 mL
Explanation: When you encounter medication dosage calculations on the HESI, you're applying the fundamental formula: desired dose divided by concentration equals volume to administer. These problems test your ability to safely calculate drug doses, a critical nursing skill. To find how many mL to give, use the formula: Volume=Desired doseConcentration\text{Volume} = \frac{\text{Desired dose}}{\text{Concentration}} Here, you need 1.2 mg and have 0.8 mg per mL available: Volume=1.2 mg0.8 mg/mL=1.5 mL\text{Volume} = \frac{1.2 \text{ mg}}{0.8 \text{ mg/mL}} = 1.5 \text{ mL} This confirms answer C (1.50 mL) is correct. Let's examine why the other options are wrong: A) 0.96 mL results from incorrectly multiplying 1.2 × 0.8 instead of dividing. This common error occurs when students confuse the setup and would deliver less medication than ordered. B) 1.20 mL happens when students assume the volume needed equals the desired dose in mg, ignoring the concentration entirely. This reflects a failure to account for the solution's strength. D) 2.00 mL comes from incorrectly dividing 0.8 by 1.2, which flips the formula completely backwards and would result in a dangerous overdose. For HESI dosage calculations, always set up your formula carefully: put what you want (desired dose) on top and what you have per mL (concentration) on the bottom. Double-check that your answer makes logical sense—if the desired dose is higher than the concentration per mL, you should need more than 1 mL.

Question 15

A nurse is calculating a patient's net fluid balance for a shift. The patient's fluid intake was 0.75 L of water and 0.4 L from an IV drip. The patient's total urinary output was measured at 1.05 L. What is the patient's net fluid balance in liters?

  1. 0.1 L (correct answer)
  2. 0.2 L
  3. 1.15 L
  4. 2.2 L
Explanation: When calculating fluid balance, you're determining whether a patient is retaining or losing fluid overall. This involves a simple equation: Net fluid balance = Total fluid intake - Total fluid output. First, calculate the total intake by adding all fluid sources: 0.75 L (water) + 0.4 L (IV) = 1.15 L total intake. The total output is given as 1.05 L of urine. Now apply the formula: 1.15 L−1.05 L=0.1 L1.15 \text{ L} - 1.05 \text{ L} = 0.1 \text{ L} This positive result means the patient retained 0.1 L more fluid than they eliminated, making A) 0.1 L correct. Let's examine why the other options are wrong. B) 0.2 L suggests you doubled the correct answer or made an arithmetic error in your calculation. C) 1.15 L is the total intake amount—this indicates you forgot to subtract the output entirely, a common oversight when working quickly. D) 2.2 L represents the sum of all intake and output values (0.75 + 0.4 + 1.05), showing confusion about whether to add or subtract these quantities. For HESI fluid balance questions, always organize your work systematically: list all intake sources, add them together, then subtract total output. Pay attention to units (mL vs. L) and convert if necessary. Remember that a positive balance means fluid retention, while a negative balance indicates fluid loss. Double-check your arithmetic, as simple calculation errors are common test traps in this topic area.

Question 16

A lab technician needs to dilute a solution. The procedure requires mixing 0.75 L of a stock solution with a diluent. The final mixture needs to have a total volume that is 3.5 times the volume of the original stock solution. What is the required final volume of the diluted solution in liters?

  1. 2.250 L
  2. 2.625 L (correct answer)
  3. 4.250 L
  4. 26.250 L
Explanation: When you encounter dilution problems on the HESI, you're working with ratios and proportional relationships. The key is identifying what information you have and what the final condition should be. Here, you start with 0.75 L of stock solution, and the problem states the final mixture volume must be 3.5 times the original stock solution volume. This means you need to calculate: 0.75 L×3.5=2.625 L0.75 \text{ L} \times 3.5 = 2.625 \text{ L} The final diluted solution volume is 2.625 L, which is answer choice B. Let's examine why the other options are incorrect. Choice A (2.250 L) represents 3 times the original volume rather than 3.5 times—this suggests misreading "3.5" as "3." Choice C (4.250 L) might result from incorrectly adding 3.5 L to the original 0.75 L, rather than multiplying by 3.5. Choice D (26.250 L) likely comes from a decimal error, perhaps calculating 0.75 × 35 instead of 0.75 × 3.5. Notice that the volume of diluent added isn't directly asked for—you're finding the total final volume. If you needed the diluent volume, you'd subtract the original stock volume from this total (2.625 L - 0.75 L = 1.875 L of diluent). For dilution problems, always read carefully to distinguish between "times larger than" (multiplication) versus "added to" (addition). The phrase "3.5 times the volume" signals multiplication, not addition.

Question 17

A patient is on a diet restricting sodium intake to 2.0 grams per day. For breakfast, the patient consumed 0.35 g of sodium, and for lunch, 0.8 g. How many grams of sodium can the patient consume for the remainder of the day?

  1. 0.85 g (correct answer)
  2. 1.15 g
  3. 1.20 g
  4. 1.65 g
Explanation: When you encounter medication dosage calculations on the HESI, you're typically dealing with straightforward arithmetic that tests your ability to accurately track cumulative intake against prescribed limits. These questions mirror real nursing scenarios where precise monitoring prevents harmful overdoses. To solve this sodium restriction problem, you need to subtract what the patient has already consumed from their daily allowance. The patient's total sodium limit is 2.0 g per day. They consumed 0.35 g at breakfast and 0.8 g at lunch, totaling 1.15 g so far. Subtracting from their daily limit: 2.0−1.15=0.852.0 - 1.15 = 0.85 grams remaining. Looking at the wrong answers: B) 1.15 g represents the total sodium already consumed, not what's remaining—this is a common trap where test-takers confuse cumulative intake with remaining allowance. C) 1.20 g might result from incorrectly subtracting only the lunch amount (2.0 - 0.8 = 1.2) while forgetting the breakfast sodium. D) 1.65 g comes from subtracting only the breakfast amount (2.0 - 0.35 = 1.65) and ignoring lunch intake entirely. The correct answer is A) 0.85 g. For HESI dosage calculations, always organize your work clearly: identify the total allowance, add up all previous intake, then subtract to find what remains. Double-check that you've included all consumed amounts—forgetting even one meal or dose is a frequent error that leads to dangerously incorrect calculations in clinical practice.

Question 18

A vial contains 4.5 mL of a liquid medication. A nurse draws up a dose of 1.25 mL. From the amount of medication remaining in the vial, how many full 0.5 mL doses can be prepared?

  1. 5
  2. 6 (correct answer)
  3. 7
  4. 9
Explanation: Medication dosage calculations require careful step-by-step problem solving to avoid costly errors in clinical practice. When working with remaining medication amounts, you need to track what's left after the initial dose is drawn. Start by calculating how much medication remains in the vial: 4.5 mL−1.25 mL=3.25 mL4.5 \text{ mL} - 1.25 \text{ mL} = 3.25 \text{ mL} Next, determine how many full 0.5 mL doses can be prepared from this remaining amount by dividing: 3.25 mL÷0.5 mL=6.53.25 \text{ mL} ÷ 0.5 \text{ mL} = 6.5 Since you can only prepare complete doses, round down to 6 full doses. This makes B the correct answer. Let's examine why the other options are incorrect: A) 5 understates the number of possible doses - you'd only use 2.5 mL of the 3.25 mL available, wasting medication unnecessarily. C) 7 requires 3.5 mL, but you only have 3.25 mL remaining after the initial draw. D) 9 would need 4.5 mL, which ignores that 1.25 mL was already removed from the original vial. The key trap here is forgetting to subtract the initial 1.25 mL dose before calculating remaining doses. Some students might divide the original 4.5 mL by 0.5 mL and get 9, but this ignores the medication already used. Study tip: Always work dosage problems in clear steps: calculate what's left, then determine how many complete doses are possible. Never round up when determining full doses - patient safety requires exact measurements.

Question 19

A clinic purchases a box containing 100 syringes for $32.50. The clinic's pricing model is to mark up the cost of each syringe by $0.15. What is the final selling price of a single syringe?

  1. $0.33
  2. $0.48 (correct answer)
  3. $3.40
  4. $32.65
Explanation: When you encounter pricing problems involving markups, you need to work systematically through two steps: find the unit cost, then add the markup to determine the final selling price. First, calculate the cost per syringe. The clinic pays $32.50 for 100 syringes, so the unit cost is $\frac{\32.50}{100} = $0.325 per syringe. Next, add the markup to find the selling price. The clinic marks up each syringe by 0.15, so the final selling price is $$\0.325 + $0.15 = $0.475$$. Rounded to the nearest cent, this equals $0.48, which is answer choice B. Looking at the incorrect options: Choice A ($0.33) represents approximately just the unit cost without including the full markup—this suggests adding only about $0.005 instead of 0.15.ChoiceC(0.15. Choice C (3.40) appears to come from incorrectly calculating the unit cost as $3.25 (perhaps dividing 32.50by10insteadof100)andthenaddingthemarkup.ChoiceD(32.50 by 10 instead of 100) and then adding the markup. Choice D (32.65) represents adding the $0.15 markup to the total box price rather than to each individual syringe. For HESI math problems involving business calculations, always break multi-step problems into clear stages: identify what you're solving for, calculate any needed unit values first, then apply the required operations. Double-check that your final answer makes logical sense—a single syringe costing over $30 should immediately signal an error in your approach.

Question 20

A patient's total urinary output over a 24-hour period was 1850.5 mL. What was the patient's average hourly output? Round to the nearest tenth of a milliliter.

  1. 7.7 mL/hr
  2. 77.0 mL/hr
  3. 77.1 mL/hr (correct answer)
  4. 77.5 mL/hr
Explanation: When you encounter urine output calculations, you're working with basic unit conversions that are essential for monitoring patient fluid balance and kidney function. These calculations help nurses assess whether a patient's urinary output falls within normal ranges. To find the average hourly output, divide the total 24-hour output by 24 hours: 1850.5 mL24 hours=77.104... mL/hr\frac{1850.5 \text{ mL}}{24 \text{ hours}} = 77.104... \text{ mL/hr}. When rounded to the nearest tenth, this gives you 77.1 mL/hr. Looking at the wrong answers: Choice A (7.7 mL/hr) represents a decimal place error - you might get this if you mistakenly divided by 240 instead of 24, or misplaced a decimal point. This output would be dangerously low and indicate severe oliguria. Choice B (77.0 mL/hr) occurs if you rounded to the nearest whole number instead of the nearest tenth as requested. Choice D (77.5 mL/hr) suggests rounding errors in your calculation - perhaps rounding intermediate steps rather than carrying out the full calculation before rounding. For HESI math questions involving urinary output, always pay close attention to the rounding instructions and double-check your decimal placement. Normal adult urine output is typically 30-50 mL/hr minimum, so your calculated answer should make clinical sense. Practice these unit conversion problems regularly, as they appear frequently on nursing exams and are fundamental to safe medication administration and fluid monitoring in clinical practice.