Health Education Systems Inc (HESI) A2 Exam Quiz: Estimating And Checking Reasonableness

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Estimating And Checking ReasonablenessQuestion 1 of 20

A wound is measured to be 5.8 cm long and 3.1 cm wide. Which of the following is the most reasonable estimate of the wound's surface area in square millimeters?

18 mm²

90 mm²

180 mm²

1800 mm²

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Health Education Systems Inc (HESI) A2 Exam Quiz

Health Education Systems Inc (HESI) A2 Exam Quiz: Estimating And Checking Reasonableness

Practice Estimating And Checking Reasonableness 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 Estimating And Checking Reasonableness, 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.

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Question 1

A wound is measured to be 5.8 cm long and 3.1 cm wide. Which of the following is the most reasonable estimate of the wound's surface area in square millimeters?

18 mm²
90 mm²
180 mm²
1800 mm² (correct answer)

Explanation: When you encounter wound measurement problems, you're working with unit conversions and area calculations—both essential skills for healthcare documentation and treatment planning. To find the wound's surface area, you multiply length × width:

5.8 \text{ cm} × 3.1 \text{ cm} = 17.98 \text{ cm}^2

. Since the question asks for the answer in square millimeters, you need to convert. Remember that 1 cm = 10 mm, so 1 cm² = 100 mm² (because

10 × 10 = 100

). Therefore:

17.98 \text{ cm}^2 × 100 = 1798 \text{ mm}^2

, which rounds to approximately 1800 mm². Looking at the wrong answers: Choice A (18 mm²) represents a major calculation error—this might result from incorrectly multiplying the original measurements in centimeters and forgetting the conversion entirely. Choice B (90 mm²) could come from converting the dimensions to millimeters first (58 mm × 31 mm = 1798 mm²) but then dividing by 20 instead of recognizing the correct answer. Choice C (180 mm²) appears to be off by exactly one decimal place, suggesting an error in the conversion factor or misplacing a decimal point. The correct answer is D (1800 mm²). Study tip: For HESI math problems involving measurements, always identify your starting units and target units first. Draw out the conversion steps—especially remember that area conversions square the linear conversion factor. Practice converting between centimeters and millimeters until it becomes automatic, as wound care documentation frequently requires these conversions.

Question 2

A patient's temperature is 102.0°F. The nurse needs to document this in Celsius. Which of the following Celsius temperatures is the most reasonable conversion?

35.8°C
38.9°C (correct answer)
41.1°C
45.5°C

Explanation: Temperature conversion between Fahrenheit and Celsius is a fundamental nursing skill you'll use regularly in clinical practice. When you encounter conversion questions on the HESI, remember that body temperature ranges help you quickly verify if your answer makes sense. To convert 102.0°F to Celsius, use the formula:

C = \frac{(F - 32) \times 5}{9}

Substituting the values:

C = \frac{(102 - 32) \times 5}{9} = \frac{70 \times 5}{9} = \frac{350}{9} = 38.9°C

This confirms that answer B (38.9°C) is correct. This temperature represents a moderate fever, which aligns with the original Fahrenheit reading. Looking at the incorrect options: Answer A (35.8°C) converts to about 96.4°F, which would indicate hypothermia rather than fever. Answer C (41.1°C) equals approximately 106°F, representing dangerously high hyperthermia that would require immediate intervention. Answer D (45.5°C) converts to 113.8°F, a temperature incompatible with life. For HESI success, memorize these key reference points: normal body temperature is 37°C (98.6°F), and fever typically starts around 38°C (100.4°F). When you're unsure about your calculation, use these benchmarks to eliminate obviously wrong answers. A 102°F fever should convert to something just above normal body temperature—making 38.9°C the only reasonable choice among the options.

Question 3

An adult male weighs 198 lbs. The estimated blood volume is 70 mL per kg of body weight. Which is the most reasonable estimate for this patient's total blood volume in liters?

4.5 L
6.3 L (correct answer)
9.0 L
13.9 L

Explanation: When you encounter blood volume calculations on the HESI, you're working with dosimetry and physiological parameters that require unit conversions and careful calculation. To find this patient's blood volume, you need to convert his weight from pounds to kilograms, then multiply by the given blood volume factor. First, convert 198 lbs to kg:

198 \text{ lbs} \div 2.2 = 90 \text{ kg}

. Next, calculate total blood volume:

90 \text{ kg} \times 70 \text{ mL/kg} = 6,300 \text{ mL}

. Finally, convert to liters:

6,300 \text{ mL} \div 1,000 = 6.3 \text{ L}

. Looking at the wrong answers: Choice A (4.5 L) represents a significant underestimate that might result from calculation errors in the conversion process or using an incorrect conversion factor. Choice C (9.0 L) suggests either skipping the pounds-to-kilograms conversion entirely (using 198 as if it were already in kg) or making errors in the multiplication. Choice D (13.9 L) indicates major computational errors, possibly combining multiple conversion mistakes or using wrong formulas altogether. The correct answer is B (6.3 L), which falls within the normal adult blood volume range of approximately 5-8 liters. Remember the conversion sequence for HESI dosimetry problems: pounds to kilograms (÷2.2), multiply by the given factor, then convert units as needed (mL to L: ÷1,000). Double-check your unit conversions—they're frequent sources of error on dosage calculation questions.

Question 4

A pediatric patient weighing 44 lbs needs a medication dosed at 25 mg/kg/day, divided into two equal doses. What is a reasonable estimate for the amount of medication in a single dose?

250 mg (correct answer)
500 mg
550 mg
1100 mg

Explanation: Pediatric dosage calculations require converting between pounds and kilograms, then applying the prescribed dose per kilogram. When you encounter medication dosing questions, always work systematically through unit conversions before calculating the final dose. First, convert the patient's weight from pounds to kilograms:

44 \text{ lbs} \div 2.2 = 20 \text{ kg}

. Next, calculate the total daily dose:

20 \text{ kg} \times 25 \text{ mg/kg/day} = 500 \text{ mg/day}

. Since this total dose is divided into two equal doses, each individual dose is:

500 \text{ mg} \div 2 = 250 \text{ mg}

. Choice A (250 mg) is correct—this represents one of the two equal doses per day. Choice B (500 mg) represents the total daily dose but fails to account for the division into two doses, a common error when students calculate correctly but miss the final step. Choice C (550 mg) suggests an error in the kilogram conversion, possibly using 2.0 instead of 2.2 as the conversion factor, then dividing by two. Choice D (1100 mg) reflects calculating the total daily dose but forgetting to convert pounds to kilograms entirely, treating 44 as if it were already in kilograms. For HESI dosage questions, always double-check your unit conversions and read carefully whether the question asks for a single dose or total daily dose. Practice the standard conversion of 2.2 lbs = 1 kg until it's automatic, and always verify that your final answer makes clinical sense for the patient's size.

Question 5

A baby weighs 7 lbs 8 oz at birth. At a check-up one month later, the baby weighs 9 lbs 4 oz. What is the most reasonable estimate for the baby's percentage weight gain?

15%
25% (correct answer)
35%
50%

Explanation: Percentage weight gain questions test your ability to calculate change relative to an original value. When you see these problems, remember that percentage change equals the difference divided by the original amount, multiplied by 100. To find this baby's percentage weight gain, first convert everything to the same units. The birth weight of 7 lbs 8 oz equals 7.5 lbs (since 8 oz = 0.5 lbs). The one-month weight of 9 lbs 4 oz equals 9.25 lbs (since 4 oz = 0.25 lbs). Next, calculate the weight gain: 9.25 - 7.5 = 1.75 lbs. Now apply the percentage formula:

\frac{1.75}{7.5} \times 100 = 23.3\%

, which rounds to approximately 25%. Looking at the wrong answers: (A) 15% is too low and might result from calculation errors or using the wrong denominator. (C) 35% significantly overestimates the gain and could come from faulty mental math or misunderstanding the percentage formula. (D) 50% represents an enormous weight gain that would be medically concerning for an infant and likely results from using the difference (1.75) without properly relating it to the original weight. The answer is (B) 25%. For percentage problems on the HESI, always double-check your unit conversions and remember the formula: change divided by original times 100. Also, use your clinical judgment—a 50% weight gain in one month would be abnormal for any patient, especially an infant.

Question 6

A drug has a half-life of 8 hours. If a patient receives an initial dose of 600 mg, what is the most reasonable estimate of the amount of drug remaining in the patient's system after 24 hours?

0 mg
75 mg (correct answer)
150 mg
300 mg

Explanation: Drug half-life questions test your understanding of exponential decay in pharmacokinetics. When you see a half-life problem, remember that every half-life period cuts the remaining drug amount in half, regardless of the starting amount. Let's work through this systematically. With a half-life of 8 hours and 24 hours total time, we have

\frac{24}{8} = 3

half-life periods. Starting with 600 mg:

After 8 hours (1 half-life): $600 \div 2 = 300$ mg
After 16 hours (2 half-lives): $300 \div 2 = 150$ mg
After 24 hours (3 half-lives): $150 \div 2 = 75$ mg

So 75 mg remains after 24 hours, making B correct. A) 0 mg assumes complete elimination, but drugs with 8-hour half-lives don't disappear entirely in 24 hours. This represents a common misconception about drug clearance. C) 150 mg is the amount remaining after only 16 hours (2 half-lives). This error occurs when students miscalculate the number of half-life periods. D) 300 mg represents the amount after just 8 hours (1 half-life). This suggests stopping the calculation too early or misunderstanding the time frame. For HESI pharmacology questions, always identify how many half-life periods have elapsed by dividing total time by the half-life duration. Then apply the "halving rule" repeatedly. Remember that drugs are never completely eliminated—there's always some amount remaining, getting smaller with each half-life period.

Question 7

A nurse needs to administer a medication at a dose of 15 mg/kg. The patient weighs 176 lbs. Which of the following is the most reasonable estimate for the total dosage the patient should receive?

590 mg
800 mg
1200 mg (correct answer)
2640 mg

Explanation: Dosage calculations are fundamental nursing skills that require converting between units and applying proportional reasoning. When you encounter weight-based dosing problems, you'll need to convert the patient's weight to kilograms, then multiply by the prescribed dose per kilogram. First, convert 176 lbs to kilograms using the conversion factor:

176 \text{ lbs} \times \frac{1 \text{ kg}}{2.2 \text{ lbs}} = 80 \text{ kg}

. Then calculate the total dose:

80 \text{ kg} \times 15 \text{ mg/kg} = 1200 \text{ mg}

. This confirms that answer C (1200 mg) is correct. Let's examine why the other options are incorrect. Answer A (590 mg) likely results from an error in the conversion process—perhaps using an incorrect conversion factor or making a calculation mistake early in the process. Answer B (800 mg) might come from forgetting to multiply by the 15 mg/kg dose after correctly converting to 80 kg, or from using an approximate but inaccurate conversion. Answer D (2640 mg) suggests the student may have skipped the pounds-to-kilograms conversion entirely and multiplied 176 by 15, treating the weight as if it were already in kilograms. Remember the essential conversion: 1 kg = 2.2 lbs. For HESI math problems, always write out your conversions step-by-step and double-check your units. Weight-based dosing errors are serious in clinical practice, so these calculations must become second nature. Practice converting common weights and memorize that 2.2 conversion factor—it appears frequently on nursing exams.

Question 8

An IV bag containing 2 liters of normal saline is set to infuse over 24 hours. A nurse looking at the IV pump settings wants to quickly check if the rate is reasonable. Which of the following flow rates in mL/hr is the most reasonable estimate?

42 mL/hr
83 mL/hr (correct answer)
125 mL/hr
200 mL/hr

Explanation: IV flow rate calculations are fundamental nursing skills that you'll encounter frequently on the HESI exam and in clinical practice. When you see questions asking you to calculate or verify infusion rates, think about converting units systematically and checking if your answer makes clinical sense. To find the correct flow rate, you need to convert the total volume to milliliters and divide by the infusion time. Start with 2 liters of normal saline:

2 \text{ L} = 2000 \text{ mL}

. Then divide by the 24-hour timeframe:

\frac{2000 \text{ mL}}{24 \text{ hours}} = 83.33 \text{ mL/hr}

. Rounding to the nearest whole number gives you approximately 83 mL/hr, making choice B correct. Now let's examine why the other options don't work. Choice A (42 mL/hr) is roughly half the correct rate—this might result from accidentally using 1 liter instead of 2 liters in your calculation. Choice C (125 mL/hr) is too high and could come from incorrectly dividing 2000 by 16 hours instead of 24 hours. Choice D (200 mL/hr) is significantly too fast and might result from dividing 2000 by 10 hours or making another major calculation error. For HESI success, always double-check your unit conversions (liters to mL, especially) and verify that your final answer seems reasonable for the clinical scenario. A helpful memory aid: 1000 mL over 12 hours equals about 83 mL/hr, so 2000 mL over 24 hours should give you the same rate.

Question 9

A clinic uses approximately 23 boxes of nitrile gloves each week. To place an order for a 90-day supply, which of the following order quantities is the most reasonable?

100 boxes
200 boxes
300 boxes (correct answer)
2070 boxes

Explanation: This question tests your ability to calculate inventory needs over an extended period, a crucial skill for healthcare supply management. When calculating supplies for a specific timeframe, you need to convert between different time units and account for the actual duration. To find the 90-day supply needed, start with the weekly usage rate of 23 boxes. Since there are 7 days in a week, you need to determine how many weeks are in 90 days:

90 \div 7 = 12.86

weeks. Multiply the weekly usage by the number of weeks:

23 \times 12.86 = 296

boxes. The closest reasonable order quantity is 300 boxes. Looking at the wrong answers: Choice A (100 boxes) would only last about 4.3 weeks, far short of the 90-day target. This represents a common error of underestimating long-term needs. Choice B (200 boxes) would last approximately 8.7 weeks, still significantly under the required 90 days. Choice D (2070 boxes) is drastically excessive—this would supply the clinic for about 90 weeks instead of 90 days, representing a calculation error where someone might have confused days with weeks. Study tip: For HESI supply calculation questions, always identify the time units carefully and convert systematically. Write out your calculation steps: weekly usage → number of weeks in the period → total needed. Double-check that your final answer makes logical sense compared to the starting usage rate.

Question 10

A patient's diet plan requires 2,200 calories per day, with 55% of those calories from carbohydrates. If carbohydrates provide 4 calories per gram, which is the most reasonable estimate for the grams of carbohydrates this patient should consume daily?

121 grams
303 grams (correct answer)
484 grams
1210 grams

Explanation: When you encounter nutritional calculation problems on the HESI, you're working with macronutrient percentages and energy conversions. These questions test your ability to translate dietary requirements into practical portions. To find the carbohydrate grams needed, you'll work through three steps. First, calculate the calories from carbohydrates:

2200 \text{ calories} \times 0.55 = 1210 \text{ calories from carbs}

. Next, convert calories to grams using the conversion factor:

1210 \text{ calories} \div 4 \text{ calories per gram} = 302.5 \text{ grams}

. Finally, round to the nearest reasonable estimate, which gives you approximately 303 grams. Choice A (121 grams) represents a common error where students might calculate 55% of 220 instead of 2200, essentially dropping a zero. Choice C (484 grams) could result from using an incorrect conversion factor, perhaps confusing carbohydrates (4 cal/g) with fats (9 cal/g), or making an arithmetic error in the division. Choice D (1210 grams) is the calorie amount without converting to grams—students sometimes stop halfway through the calculation and report calories instead of the requested grams. Remember the macronutrient conversion factors: carbohydrates and proteins both provide 4 calories per gram, while fats provide 9 calories per gram. On HESI nutrition questions, always double-check your units—the question asks for grams, not calories. Setting up your calculation systematically (percentage → calories → grams) helps avoid these common pitfalls.

Question 11

A dose of 0.65 mL of a vaccine needs to be administered. Which of the following syringes would be the most unreasonable choice for ensuring an accurate measurement?

A 1 mL tuberculin syringe, marked in hundredths of a mL.
A 3 mL syringe, marked in tenths of a mL.
A 5 mL syringe, marked in two-tenths of a mL.
A 20 mL syringe, marked in whole mL. (correct answer)

Explanation: When administering medications, syringe selection is crucial for accurate dosing. The key principle is that your syringe's measurement markings must be precise enough to measure the required dose accurately, and the syringe size should be appropriate for the volume being administered. For a 0.65 mL vaccine dose, you need a syringe that can measure to at least the hundredths place (0.01 mL) to ensure accuracy. Option D, the 20 mL syringe marked in whole mL increments, makes this impossible. This syringe can only measure 1 mL, 2 mL, 3 mL, etc. You cannot accurately measure 0.65 mL when your smallest increment is 1.0 mL. You'd have to estimate between the 0 mL and 1 mL marks, introducing significant measurement error. Option A is ideal because tuberculin syringes marked in hundredths allow precise measurement of 0.65 mL. Option B works well since you can accurately read 0.65 mL when markings show tenths (0.6 mL and 0.7 mL lines let you interpolate 0.65 mL). Option C is acceptable because markings at 0.6 mL and 0.8 mL intervals still allow reasonable estimation of 0.65 mL. The 20 mL syringe's large volume capacity combined with whole mL markings creates a double problem: the measurement increments are too large, and the syringe itself is oversized for such a small dose. Study tip: Always choose the smallest appropriate syringe with the finest measurement markings for your dose. For doses under 1 mL, tuberculin syringes are typically your best choice for accuracy.

Question 12

A patient on a 1.5 L daily fluid restriction has consumed a 12-oz can of soda, a 6-oz cup of yogurt, and 500 mL of water with medications. Using the approximation 1 oz ≈ 30 mL, what is a reasonable estimate of the fluid remaining for the rest of the day?

460 mL (correct answer)
720 mL
960 mL
1040 mL

Explanation: When you encounter fluid restriction problems, you're testing your ability to convert between measurement units and track cumulative intake against prescribed limits. This is a critical skill for monitoring patients with conditions like heart failure or kidney disease. Let's calculate the patient's fluid consumption step by step. Start by converting everything to the same unit (mL). The patient consumed:

12 oz soda: $12 \times 30 = 360 \text{ mL}$
6 oz yogurt: $6 \times 30 = 180 \text{ mL}$
500 mL water (already in mL)

Total consumed:

360 + 180 + 500 = 1040 \text{ mL}

The daily restriction is 1.5 L, which equals 1500 mL. Remaining fluid allowance:

1500 - 1040 = 460 \text{ mL}

Looking at the wrong answers: Answer B (720 mL) likely results from forgetting to include the yogurt in calculations or using an incorrect conversion factor. Answer C (960 mL) suggests someone may have miscalculated the soda conversion or made an arithmetic error in subtraction. Answer D (1040 mL) is actually the total amount already consumed, not the remaining allowance—this represents confusing what's been used with what's left. The correct answer is A (460 mL). For HESI success, always convert all measurements to the same unit first, double-check your arithmetic, and clearly distinguish between "consumed" versus "remaining" when the question asks for fluid allowance. Remember that yogurt, ice cream, and similar semi-solids count as fluids in restriction calculations.

Question 13

A solution needs to be diluted from a 12% stock concentration to a 3% working concentration. To make 400 mL of the 3% solution, a student calculates that 150 mL of the stock solution is needed. Is this calculation reasonable?

No, the amount of stock solution is too high. (correct answer)
No, the amount of stock solution is too low.
Yes, the calculation is correct and reasonable.
No, this dilution is not possible with the given stock.

Explanation: When you encounter dilution problems, you're working with the principle that the amount of solute remains constant—you're just adding solvent to reduce concentration. The key formula is

C_1V_1 = C_2V_2

, where the initial concentration times initial volume equals the final concentration times final volume. Let's check this calculation. You need 400 mL of 3% solution from a 12% stock. Using the dilution formula:

12\% \times V_1 = 3\% \times 400\text{ mL}

. Solving for

V_1

V_1 = \frac{3\% \times 400\text{ mL}}{12\%} = \frac{1200}{12} = 100\text{ mL}

. The student calculated 150 mL, which is 50% more than needed. Looking at the answer choices: A is correct—150 mL is too high. Using 150 mL would create a solution stronger than 3%. B is wrong because 150 mL exceeds the correct amount of 100 mL, so it's not too low. C is incorrect since the calculation contains a significant error—the student likely made an arithmetic mistake or used the wrong formula setup. D is wrong because this dilution is absolutely possible; you're going from a higher to lower concentration, which is standard dilution practice. A quick reasonableness check helps catch these errors: since you're diluting from 12% to 3% (a 4-fold dilution), you should need about ¼ of your final volume as stock solution. That's roughly 100 mL, making 150 mL clearly excessive. Always verify dilution calculations with this mental math check.

Question 14

An order is written for 500 mg of an antibiotic to be given every 8 hours for 7 days. The pharmacy dispenses 250 mg tablets. A new nurse calculates that 42 tablets are needed. Is this calculation reasonable?

Yes, the calculation is correct. (correct answer)
No, the calculation is off by one day's worth of medication.
No, exactly half the required number of tablets was calculated.
No, exactly double the required number of tablets was calculated.

Explanation: When you encounter medication calculation questions, you need to work systematically through the dosing requirements and tablet strength to determine the total number of tablets needed. Let's verify the nurse's calculation step by step. The order calls for 500 mg every 8 hours for 7 days. First, determine how many doses are needed:

\frac{24 \text{ hours}}{8 \text{ hours}} = 3 \text{ doses per day}

. Over 7 days, that's

3 \times 7 = 21 \text{ total doses}

. Next, calculate tablets per dose. With 250 mg tablets available and 500 mg needed per dose:

\frac{500 \text{ mg}}{250 \text{ mg}} = 2 \text{ tablets per dose}

. Finally, find the total tablets needed:

21 \text{ doses} \times 2 \text{ tablets} = 42 \text{ tablets}

. The nurse's calculation is correct. Choice A is right because 42 tablets is indeed the accurate calculation. Choice B is wrong because the calculation isn't off by one day's worth (which would be 6 tablets, making the total 36 or 48). Choice C is incorrect because half of 42 would be 21 tablets, not what was calculated. Choice D is wrong because double would be 84 tablets, far from the nurse's answer. Study tip: Break medication calculations into clear steps: doses per day × total days = total doses, then total doses × tablets per dose = total tablets needed. This systematic approach prevents calculation errors that are common traps on the HESI.

Question 15

A nurse must mix a cleaning solution by combining 1 part concentrated bleach with 7 parts water. To prepare a total of 2 gallons of solution, what is a reasonable estimate for the amount of concentrated bleach needed?

1 quart (correct answer)
2 quarts
4 quarts
8 quarts

Explanation: When you encounter ratio and proportion problems, the key is to identify the parts of the mixture and set up the relationship correctly. This question involves mixing concentrated bleach with water in a 1:7 ratio. First, determine what "1 part bleach to 7 parts water" means for the total mixture. You have 1 part bleach + 7 parts water = 8 total parts. This means bleach makes up

\frac{1}{8}

of the final solution. To find the amount of bleach needed for 2 gallons of total solution, calculate:

2 \text{ gallons} \times \frac{1}{8} = \frac{2}{8} = \frac{1}{4} \text{ gallon}

Since 1 gallon equals 4 quarts,

\frac{1}{4}

gallon equals 1 quart. Looking at the answer choices: A) 1 quart is correct based on our calculation. B) 2 quarts would represent

\frac{1}{4}

of the solution, which corresponds to a 1:3 ratio, not 1:7. C) 4 quarts (1 gallon) would be half the total solution, representing a 1:1 ratio. D) 8 quarts (2 gallons) would mean using only concentrated bleach with no water, which completely ignores the dilution requirement. For HESI ratio problems, always identify what fraction each component represents of the total mixture, then multiply that fraction by the desired total amount. Double-check by ensuring all parts add up to your target total—here, 1 quart bleach + 7 quarts water = 8 quarts = 2 gallons.

Question 16

A nurse is preparing to administer 0.75 mg of medication from a vial containing 2 mg/mL. The nurse calculates that 0.375 mL should be drawn up. Before administering, which estimation method would best verify the reasonableness of this calculation?

Since 0.75 is approximately 3/4 of 1 mg, and 1 mg would require 0.5 mL, the answer should be close to 3/4 × 0.5 = 0.375 mL
Since 0.75 is less than 2 mg, the volume should be less than 1 mL, so 0.375 mL seems reasonable for any dose under 2 mg
Since the concentration is 2 mg/mL, dividing 0.75 by 2 gives approximately 0.4, which is close enough to 0.375 mL to be reasonable (correct answer)
Since 0.75 mg is about half of 1.5 mg, and 1.5 mg would need 0.75 mL, the answer should be approximately 0.4 mL

Explanation: The most direct estimation method is to use the basic formula: volume = dose ÷ concentration. Here, 0.75 ÷ 2 = 0.375 mL exactly, but for estimation purposes, 0.75 ÷ 2 ≈ 0.4 mL, which confirms the calculated answer is reasonable. Choice A uses an unnecessarily complex approach with fractions. Choice B is too vague and doesn't provide a specific check. Choice D uses an arbitrary comparison point (1.5 mg) that complicates the estimation unnecessarily.

Question 17

A nurse calculates that an IV infusion of 1000 mL should run over 8 hours at a rate of 125 mL/hr. Before setting the pump, which method provides the most reliable check of this calculation's reasonableness?

Since 8 hours × 125 mL/hr = 1000 mL exactly, the calculation is mathematically sound and requires no further verification
Estimate using 100 mL/hr: 8 × 100 = 800 mL, which is reasonably close to 1000 mL given the approximation used
Check that 1000 ÷ 8 = 125 by estimating: 1000 ÷ 10 = 100, so 1000 ÷ 8 should be somewhat more, around 125 (correct answer)
Verify that 125 mL/hr is within the typical range for adult IV rates, which confirms the calculation is clinically reasonable

Explanation: The best verification method checks the division: 1000 ÷ 8 = 125. The estimation 1000 ÷ 10 = 100 provides a reference point, and since 8 < 10, the result should be > 100, making 125 mL/hr reasonable. Choice A performs exact calculation rather than estimation. Choice B uses too much rounding (125 to 100) and doesn't directly verify the original calculation. Choice D focuses on clinical reasonableness rather than mathematical verification of the specific calculation.

Question 18

A patient's fluid intake for a 12-hour shift is recorded as: 240 mL juice, 180 mL water, 120 mL broth, and 200 mL milk. The nurse quickly estimates the total as approximately 750 mL. What is the best method to check if this estimate is reasonable?

Round each amount to the nearest 50: 250 + 200 + 100 + 200 = 750 mL, confirming the estimate is accurate within acceptable limits
Add the first two amounts (420 mL) and the last two amounts (320 mL) to get 740 mL, showing the estimate is very close (correct answer)
Round all amounts to the nearest 100: 200 + 200 + 100 + 200 = 700 mL, which is reasonably close to the 750 mL estimate
Since all amounts are between 100-250 mL, multiply the average (approximately 185 mL) by 4 to get about 740 mL, confirming the estimate

Explanation: The most reliable check is to group and add systematically: (240 + 180) + (120 + 200) = 420 + 320 = 740 mL. This gives the exact total and shows the 750 mL estimate is very close (within 10 mL). Choice A introduces rounding errors that happen to work but aren't as precise. Choice C uses excessive rounding that loses accuracy. Choice D requires calculating an average first, adding unnecessary complexity to the verification process.

Question 19

An insulin calculation shows that a patient needs 8.4 units of insulin based on a sliding scale protocol for a blood glucose of 284 mg/dL. The protocol states: give 1 unit for every 20 mg/dL over 200 mg/dL. Which method best verifies this calculation?

The excess glucose is 284 - 200 = 84 mg/dL, and 84 ÷ 20 = 4.2 units, which doesn't match the calculated 8.4 units
Estimate: 284 is about 280, so 280 - 200 = 80, and 80 ÷ 20 = 4 units, suggesting 8.4 units is approximately double what's needed (correct answer)
Round 284 to 300: 300 - 200 = 100, and 100 ÷ 20 = 5 units, which is reasonably close to 8.4 units given the rounding
Since 284 mg/dL is significantly elevated, 8.4 units seems clinically appropriate regardless of the specific calculation details

Explanation: The estimation approach (284 ≈ 280) gives: 280 - 200 = 80 mg/dL over target, and 80 ÷ 20 = 4 units. This reveals that 8.4 units is about double the correct dose, indicating a calculation error. Choice A gives the exact calculation (4.2 units) but doesn't use estimation methods. Choice C uses excessive rounding that masks the error. Choice D ignores the mathematical verification entirely, focusing only on clinical judgment.

Question 20

A nurse calculates that a patient who weighs 176 lbs needs 480 mL of contrast dye, based on a dosing formula of 6 mL per kilogram. To check if this calculation is reasonable, which approach would be most appropriate?

Convert 176 lbs to kg: 176 ÷ 2.2 ≈ 80 kg, then 80 kg × 6 mL/kg = 480 mL, confirming the calculation exactly
Estimate the weight as 180 lbs ≈ 90 kg, then 90 × 6 = 540 mL, suggesting the calculated 480 mL is somewhat low but reasonable
Use the approximation that 176 lbs ≈ 175 lbs ≈ 80 kg, then 80 × 6 = 480 mL, which matches the calculation exactly
Since 176 lbs is close to 180 lbs, and 180 lbs equals approximately 82 kg, then 82 × 6 = 492 mL, making 480 mL reasonable (correct answer)

Explanation: The most effective estimation rounds 176 lbs to 180 lbs for easier conversion: 180 ÷ 2.2 ≈ 82 kg (since 180 ÷ 2 = 90, and 2.2 > 2, the result should be less than 90). Then 82 × 6 = 492 mL, which is very close to 480 mL. Choice A provides exact calculation rather than estimation. Choice B incorrectly converts 180 lbs to 90 kg (should be ≈82 kg). Choice C uses an exact conversion coincidentally but doesn't demonstrate the estimation process clearly.