Middle School Math Quiz: Find Percent Of A Quantity
20 questions · exam conditions
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Find Percent Of A QuantityQuestion 1 of 20

A school cafeteria ordered 240 apples for the week. By Wednesday, they had used 35% of the apples. On Thursday, they used 20% of the original order. How many apples were left after Thursday?

108 apples
132 apples
156 apples
84 apples
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Middle School Math Quiz

Middle School Math Quiz: Find Percent Of A Quantity

Practice Find Percent Of A Quantity in Middle School Math 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 Find Percent Of A Quantity, giving you a quick way to practice the rules, question types, and explanations that matter most for Middle School Math.

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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 school cafeteria ordered 240 apples for the week. By Wednesday, they had used 35% of the apples. On Thursday, they used 20% of the original order. How many apples were left after Thursday?

  1. 108 apples (correct answer)
  2. 132 apples
  3. 156 apples
  4. 84 apples
Explanation: First find apples used by Wednesday: 35% of 240 = 0.35 × 240 = 84 apples. Then find apples used Thursday: 20% of 240 = 0.20 × 240 = 48 apples. Total used = 84 + 48 = 132 apples. Apples left = 240 - 132 = 108 apples. Choice B incorrectly shows total used instead of remaining. Choice C subtracts only Wednesday's usage. Choice D shows only Wednesday's usage.

Question 2

A water tank holds 500 gallons when full. Due to a small leak, it loses 12% of its current contents each day. If the tank starts completely full, how many gallons will remain after 2 days?

  1. 380 gallons remaining
  2. 440 gallons remaining
  3. 388 gallons remaining (correct answer)
  4. 320 gallons remaining
Explanation: After each day, 88% remains (100% - 12% = 88%). Day 1: 88% of 500 = 0.88 × 500 = 440 gallons. Day 2: 88% of 440 = 0.88 × 440 = 387.2 ≈ 388 gallons. Choice A subtracts 12% twice from original amount incorrectly. Choice B shows amount after only 1 day. Choice D incorrectly compounds the loss as 24% of original.

Question 3

A basketball player made 75% of their free throws. If they made 18 free throws, how many free throws did they attempt in total?

  1. 24 (correct answer)
  2. 72
  3. 1350
  4. 13.5
Explanation: This question tests finding the whole given a part and its percent, where 18 made free throws are 75% of total attempts. Percent is per hundred, so 75% = 0.75. Divide the part by the rate: 18 ÷ 0.75 = 24. Set up 0.75 × a = 18 and solve for a. Errors include multiplying 18 × 0.75 = 13.5 or using 75 as 7.5. Steps: identify 18 as 75% or 0.75, divide 18 by 0.75 to get 24, verify 0.75 × 24 = 18. Useful in sports stats, remember 75% = 0.75.

Question 4

A notebook costs $60. The store gives a 15%15\% discount. How much money is the discount?

  1. $0.90
  2. $9 (correct answer)
  3. $51
  4. $15
Explanation: This question tests finding a percent of a quantity for a discount, such as 15% of 6060 equals 99 using the rate 15/10015/100 multiplied by the cost. Percent means a rate per 100, so 15% is 0.150.15 as a decimal, and to find the discount, multiply 0.15×60=90.15 \times 60 = 9; this is common in shopping contexts where you calculate savings. For example, for a 15% discount on 6060, convert to 0.150.15 and multiply by 6060 to get 99 off. The correct calculation is 0.15×60=90.15 \times 60 = 9, so the discount is 99. A common error is calculating the sale price instead, like 60−9=5160 - 9 = 51, or using 15 as a whole number: 15×60=90015 \times 60 = 900, or mistaking for 1.5% leading to 0.015×60=0.900.015 \times 60 = 0.90. To find the percent of a quantity, convert percent to decimal (15%=0.1515\% = 0.15), multiply by the quantity (0.15×60=90.15 \times 60 = 9), and interpret as the discount amount. In discount scenarios, remember equivalents like 10% = 0.100.10 and avoid multiplying by the percent without converting to decimal.

Question 5

A hoodie costs $50 and is on sale for 20% off. What is the price after the discount?

  1. $30
  2. $10
  3. $40 (correct answer)
  4. $60
Explanation: This question tests finding the percent of a quantity for a discount and then subtracting, where a 20% discount on $50 gives the sale price. Percent is per hundred, so 20% is 0.20. First, find the discount: 0.20 × 50 = $10, then subtract from original: 50 - 10 = $40. You can also multiply by the remaining percent: 80% or 0.80 × 50 = $40. Errors include subtracting 20 directly to get $30 or multiplying by 20 to get $1000. Steps: convert 20% to 0.20, calculate discount as 0.20 × 50 = 10, subtract to get $40, and verify 20% of 40 is not needed but confirms logic. This is common in shopping, and remember 20% = 0.20.

Question 6

A hoodie costs $50. It is on sale for 20% off. What is the sale price?

  1. $60
  2. $40 (correct answer)
  3. $10
  4. $30
Explanation: This question tests finding the percent of a quantity for a discount, where 20% off $50 means calculating the discount as 0.20 × 50 = $10, then subtracting to get the sale price of $40, or directly multiplying by 80% (0.80 × 50 = 40). Percent as a rate per 100: 20% off is 0.20 discount, or remaining is 80% or 0.80. For example, 20% off $50: discount is 0.20 × 50 = $10, sale price $50 - $10 = $40. The correct calculation is 0.80 × 50 = 40, so the sale price is $40. A common error is answering with the discount amount like $10 instead of the final price, or adding instead of subtracting. To find the sale price: (1) convert discount percent to decimal (20% → 0.20), (2) calculate discount 0.20 × 50 = 10, (3) subtract from original $50 - $10 = $40, or use 0.80 × 50 directly. This is useful in shopping contexts like sales and promotions.

Question 7

A meal costs $40. You leave a 15%15\% tip based on the meal cost. How much is the tip?

  1. $60
  2. $6 (correct answer)
  3. $0.60
  4. $15
Explanation: This question tests finding a percent of a quantity for a tip, such as 15%15\% of 4040 equals 66 using 15/100×4015/100 \times 40. Percent is per 100, so 15%=0.1515\% = 0.15, multiply 0.15×40=60.15 \times 40 = 6; common in restaurant bills. For example, 15%15\% tip on 4040: 0.15×40=60.15 \times 40 = 6. The correct calculation is 0.15×40=60.15 \times 40 = 6, so the tip is 66. A common error is using 15 without conversion: 15×40=60015 \times 40 = 600, or dividing 40÷15≈2.6740 \div 15 \approx 2.67, or mistaking for 1.5%=0.015×40=0.601.5\% = 0.015 \times 40 = 0.60. To calculate, convert to decimal (15%=0.1515\% = 0.15), multiply (0.15×40=60.15 \times 40 = 6), and interpret as tip. In tipping contexts, recall 10%=0.1010\% = 0.10, avoiding errors like decimal point mistakes.

Question 8

A recipe uses 12 cups of flour, and 25%25\% of the flour is whole wheat flour. How many cups of whole wheat flour are used?

  1. 3 cups (correct answer)
  2. 25 cups
  3. 48 cups
  4. 0.3 cups
Explanation: This question tests finding a percent of a quantity, such as 25% of 12 cups equals 3 cups using 25/100 × 12. Percent means per 100, so 25% = 0.25, multiply 0.25 × 12 = 3; like portions in recipes. For example, 25% whole wheat in 12 cups flour: 0.25 × 12 = 3 cups. The correct calculation is 0.25 × 12 = 3, so 3 cups of whole wheat flour. A common error is dividing: 12 ÷ 25 = 0.48, or using 25 without conversion: 25 × 12 = 300, or mistaking for 2.5% = 0.025 × 12 = 0.3. To find the part, convert to decimal (25% = 0.25), multiply (0.25 × 12 = 3), and interpret. Common in recipes, use equivalents like 25% = 1/4, avoiding operation errors.

Question 9

In a video game, you earned 25% of the total points for completing a quest. If 25% equals 20 points, what is the total number of points possible?

  1. 45
  2. 80 (correct answer)
  3. 800
  4. 5
Explanation: This question tests finding the whole given a part and its percent, where 20 points is 25% of the total points in a video game. Percent as a rate per 100 means 25% is 0.25. To find the whole, divide the part by the percent rate: 20 ÷ 0.25 = 80. You can set up the equation 0.25 × w = 20 and solve for w. A common error is multiplying instead of dividing, like 20 × 0.25 = 5, or confusing with 25 as a whole number. Steps: identify 20 as 25% or 0.25 of the whole, divide 20 by 0.25 to get 80, and check by calculating 0.25 × 80 = 20. This is useful in contexts like scores or progress tracking, and remember common conversions like 25% = 0.25.

Question 10

Marcus spent 40% of his allowance on a video game and had $12 left over. What was his original allowance?

  1. $30.00
  2. $20.00 (correct answer)
  3. $18.00
  4. $4.80
Explanation: If Marcus spent 40% of his allowance, he had 60% left over. Since 60% of his allowance equals $12, we can set up: 0.60 × allowance = $12. Therefore, allowance = $12 ÷ 0.60 = $20. Choice A incorrectly adds $12 to 40% of unknown amount. Choice C assumes $12 is 40% instead of 60%. Choice D incorrectly calculates 40% of $12.

Question 11

A student answered 75% of 120 questions correctly on a practice set. How many questions did the student answer correctly?

  1. 75
  2. 160
  3. 45
  4. 90 (correct answer)
Explanation: This question tests finding the percent of a quantity, such as 75% of 120 questions answered correctly, calculated as 0.75 × 120 = 90. Percent means per hundred, so 75% is 0.75; multiply by the total to find the part, 0.75 × 120 = 90. For example, 75% of 120 is 0.75 × 120 = 90 correct answers. The correct calculation is 0.75 × 120 = 90, so 90 questions. Common mistakes include using 75 as a whole number like 75 × 120 = 9000, or dividing 120 ÷ 75 = 1.6. To find the part: (1) convert percent to decimal (75% → 0.75), (2) multiply by quantity (0.75 × 120 = 90), (3) interpret as 90 correct. Memorize conversions like 75% = 0.75 for scores and tests.

Question 12

A video game has 150 levels. A player has completed 20% of the levels. How many levels has the player completed?

  1. 3000
  2. 30 (correct answer)
  3. 20
  4. 75
Explanation: This question tests finding the percent of a quantity, such as 20% of 150 levels completed, calculated as 0.20 × 150 = 30. Percent as a rate per 100: 20% is 0.20; multiply by the total, 0.20 × 150 = 30. For example, 20% of 150 is 0.20 × 150 = 30 levels. The correct calculation is 0.20 × 150 = 30, so 30 levels completed. A common error is using 20 as whole number like 20 × 150 = 3000, or dividing 150 ÷ 20 = 7.5. To find the part: (1) convert percent to decimal (20% → 0.20), (2) multiply by quantity (0.20 × 150 = 30), (3) interpret as 30 completed. Applies to progress like in games or tasks.

Question 13

At the start of the year, a savings account had $200. Each month, the account earns 2% interest on the current balance, and then $15 is withdrawn. What will be the account balance after the interest is earned and withdrawal is made in the first month?

  1. $187.00 account balance
  2. $191.00 account balance
  3. $204.00 account balance
  4. $189.00 account balance (correct answer)
Explanation: When you see a problem involving percentage calculations followed by additions or subtractions, work through each step in the exact order given. This tests your ability to apply percentages to real-world scenarios like banking. Start with the initial balance of $200. First, calculate the 2% interest earned. To find 2% of $200, multiply: $200 × 0.02 = $4. Add this interest to get the new balance: $200 + $4 = $204. Then subtract the $15 withdrawal: $204 - $15 = $189. Choice A ($187) represents the error of subtracting the withdrawal before adding interest: $200 - $15 = $185, then $185 × 1.02 = $188.70, rounded to $187. This incorrect order changes the final result because you're calculating interest on the wrong amount. Choice B ($191) comes from miscalculating the interest as 1% instead of 2%: $200 × 1.01 = $202, then $202 - $15 = $187. Some students might round this incorrectly or make arithmetic errors to reach $191. Choice C ($204) shows the balance after earning interest but before making the withdrawal. This happens when students forget to complete all steps in a multi-step problem. The correct answer is D ($189). Study tip: In percentage problems with multiple operations, always follow the exact sequence described. Write down each step to avoid skipping parts or changing the order, which can significantly affect your final answer.

Question 14

A hoodie costs $50 and is on sale for 20%20\% off. What is the sale price of the hoodie?

  1. $100
  2. $40 (correct answer)
  3. $10
  4. $30
Explanation: This question tests finding a percent of a quantity for a discount and then the sale price, like 20% off $50 means discount of 10, so pay $40. Percent is per 100, so 20% = 0.20, discount = 0.20 × 50 = 10, sale price = 50 - 10 = 40; or directly 80% of original: 0.80 × 50 = 40. For example, 20% off $50: subtract discount 10 from 50 to get $40 sale price. The correct calculation is 50 - (0.20 × 50) = 40, so the sale price is $40. A common error is giving the discount as answer (10), or adding instead of subtracting (50 + 10 = 60), or using 20% of sale price incorrectly. To find sale price, calculate discount (0.20 × 50 = 10), subtract from original (50 - 10 = 40), or multiply by (1 - 0.20) = 0.80 × 50 = 40. In shopping, remember percents like 20% = 0.20, avoiding confusion between discount and final price.

Question 15

A school club sold 80 tickets for a game. If 30% of the tickets were sold to students, how many student tickets were sold?

  1. 30
  2. 24 (correct answer)
  3. 2.4
  4. 240
Explanation: This question tests finding the percent of a quantity, such as calculating 30% of 80 tickets to determine how many were sold to students, using the rate 30/100 multiplied by the quantity, which equals 24. Percent means per hundred, so 30% is 30 per 100 or 0.30 as a decimal; to find the part, multiply the decimal by the whole quantity, like 0.30 × 80 = 24. For example, 30% of 80 is calculated by converting 30% to 0.30 and multiplying by 80 to get 24, meaning 24 student tickets were sold. The correct calculation is 0.30 × 80 = 24, so the answer is 24. A common error is treating the percent as a whole number without converting, like multiplying 30 × 80 = 2400, or dividing instead of multiplying, such as 80 ÷ 30 = about 2.67. To find the part: (1) convert percent to decimal (30% → 0.30), (2) multiply by the quantity (0.30 × 80 = 24), (3) interpret that 24 tickets were sold to students. Remember common percents like 10% = 0.10, 25% = 0.25, and apply in contexts like ticket sales or portions of groups.

Question 16

A student scored 80 points on a test. What is 30%30\% of 80?

  1. 24 (correct answer)
  2. 30
  3. 2.4
  4. 2400
Explanation: This question tests finding a percent of a quantity, such as calculating 30% of 80, which equals 24 using the rate 30/10030/100 multiplied by the quantity. Percent means a rate per 100, so 30% is 30 per 100 or 0.30 as a decimal (convert by dividing 30 by 100), and to find the part, multiply the decimal by the quantity: 0.30×80=240.30 \times 80 = 24, or using fractions, 30/100×80=2400/100=2430/100 \times 80 = 2400/100 = 24. For example, to find 30% of 80, convert 30% to 0.30 and multiply by 80 to get 24, which means 24 is the portion representing 30% of the total 80 points. The correct calculation is 30% of 80: 0.30×80=240.30 \times 80 = 24, so the answer is 24. A common error is treating the percent as a whole number without converting, like multiplying 30×80=240030 \times 80 = 2400, or dividing instead of multiplying, such as 80÷30=about 2.6780 \div 30 = \text{about } 2.67, or confusing it with 3% instead of 30% leading to 0.03×80=2.40.03 \times 80 = 2.4. To find a percent of a quantity, first convert the percent to a decimal by dividing by 100 (30%=0.3030\% = 0.30), then multiply by the quantity (0.30×80=240.30 \times 80 = 24), and interpret the result as the part of the whole. Common percents include 10%=0.1010\% = 0.10, 25%=0.2525\% = 0.25, and 50%=0.5050\% = 0.50; in contexts like test scores, this helps determine portions, but avoid mistakes like forgetting to convert the percent to a decimal.

Question 17

A jar has 36 marbles, and 75%75\% of them are blue. How many blue marbles are in the jar?

  1. 12
  2. 0.27
  3. 2700
  4. 27 (correct answer)
Explanation: This question tests finding a percent of a quantity, such as 75% of 36 marbles equals 27 blue ones using 75/100 × 36. Percent means per 100, so 75% = 0.75, and multiply 0.75 × 36 = 27; fractions work too: 75/100 = 3/4, and 3/4 × 36 = 27. For example, 75% of 36: 0.75 × 36 = 27 blue marbles. The correct calculation is 0.75 × 36 = 27, so there are 27 blue marbles. A common error is using 75 as whole: 75 × 36 = 2700, or dividing 36 ÷ 75 = 0.48, or mistaking for 7.5% = 0.075 × 36 ≈ 2.7. To find the part, convert percent to decimal (75% = 0.75), multiply by quantity (0.75 × 36 = 27), and verify. Remember 75% = 0.75 in contexts like proportions, avoiding decimal errors like using 0.075.

Question 18

A class collected 90 canned goods for a food drive. If 40% of the cans were collected on the last day, how many cans were collected on the last day?

  1. 36 (correct answer)
  2. 40
  3. 3.6
  4. 3600
Explanation: This question tests finding the percent of a quantity, calculating 40% of 90 canned goods collected on the last day. Percent is per hundred, so 40% = 0.40. Multiply 0.40 by 90 to get 36. Or (40/100) × 90 = 36. Errors include multiplying by 40 to get 3600 or dividing 90 by 40 to get 2.25. Steps: convert 40% to 0.40, multiply by 90 for 36, and understand 36 cans on the last day. Applies to collections or drives, remember 40% = 0.40.

Question 19

A meal costs $60. You leave a 15% tip based on the meal cost. How much is the tip?

  1. $90
  2. $9 (correct answer)
  3. $0.90
  4. $15
Explanation: This question tests finding the percent of a quantity in a real-world context, like calculating a 15% tip on a $60 meal, using $ 15/100 \times 60 = 9 .Percentmeansperhundred,so15. Percent means per hundred, so 15% is 0.15; multiply by the quantity to find the tip, 0.15 \times 60 = 9 .Forexample,a15. For example, a 15% tip on $60 is $ 0.15 \times 60 = 9 . The correct calculation is 0.15×60=90.15 \times 60 = 9, so the tip is $9. Common errors include forgetting to convert percent to decimal, like $ 15 \times 60 = 900 ,orusingthewrongdecimallike, or using the wrong decimal like 0.015 \times 60 = 0.90 .Tofindthepart:(1)convertpercenttodecimal(. To find the part: (1) convert percent to decimal ( 15% \to 0.15 ),(2)multiplybythecost(), (2) multiply by the cost ( 0.15 \times 60 = 9 $), (3) interpret as $9 tip. Tips are a common percent application, along with discounts and taxes.

Question 20

In a class, 18 students are wearing sneakers. This is 30% of the class. How many students are in the class?

  1. 60 (correct answer)
  2. 6
  3. 54
  4. 0.6
Explanation: This question tests finding the whole given a part and percent, where 18 students wearing sneakers are 30% of the class, so total class is 18 ÷ 0.30 = 60. Percent as a rate: 30% is 0.30; solve 0.30 × w = 18 by dividing w = 18 ÷ 0.30 = 60. For example, if 18 is 30% of the class, divide 18 ÷ 0.30 = 60 students total. The correct calculation is 18 ÷ 0.30 = 60, so 60 students. A common error is multiplying 18 × 0.30 = 5.4 instead of dividing, or using 30 as 3.0. To find the whole: (1) convert percent to decimal (30% → 0.30), (2) set up 0.30 × w = 18, (3) divide 18 ÷ 0.30 = 60, (4) verify 0.30 × 60 = 18. Applies to class portions or surveys.