ACT Math Quiz: Percents
20 questions · exam conditions
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PercentsQuestion 1 of 20

A student's score increases from 6464 to 8080. What is the percent increase based on the original score?

16%16\%
20%20\%
25%25\%
125%125\%
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ACT Math Quiz

ACT Math Quiz: Percents

Practice Percents in ACT 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 Percents, giving you a quick way to practice the rules, question types, and explanations that matter most for ACT Math.

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 student's score increases from 6464 to 8080. What is the percent increase based on the original score?

  1. 16%16\%
  2. 20%20\%
  3. 25%25\% (correct answer)
  4. 125%125\%
Explanation: We need to find the percent increase from 64 to 80. Percent change is (new value - original value)/original value × 100. Here: (80 - 64)/64 × 100 = 16/64 × 100 = 0.25 × 100 = 25%. Choice B (20%) incorrectly uses the wrong base for calculation, and choice A (16%) gives just the difference without converting to a percent.

Question 2

If a $50 shirt is on sale for 30% off, what is the sale price?

  1. $15
  2. $35 (correct answer)
  3. $20
  4. $30
Explanation: This question asks for the sale price after a 30% discount on a $50 shirt. First find the discount amount: 30% of $50 = 0.30 × $50 = $15. Then subtract from the original price: $50 - $15 = 35.ChoiceA(35. Choice A (15) incorrectly gives just the discount amount rather than the final sale price.

Question 3

What is 30% of 90?

  1. 27 (correct answer)
  2. 30
  3. 20
  4. 18
Explanation: This question asks us to find 30% of 90. To find a percent of a number, convert the percent to a decimal and multiply: 30%=0.3030\% = 0.30. Calculate: 0.30×90=270.30 \times 90 = 27. Choice B (30) represents the error of confusing the percent value with the result.

Question 4

Convert 75%75\% to a fraction in simplest form.

  1. 75100\frac{75}{100}
  2. 34\frac{3}{4} (correct answer)
  3. 43\frac{4}{3}
  4. 75\frac{7}{5}
Explanation: We need to convert 75% to a fraction in simplest form. First write 75% as 75/100, then simplify by finding the greatest common factor: 75/100 = (75÷25)/(100÷25) = 3/4. Choice A (75/100) is not in simplest form, and choices C and D represent values greater than 1.

Question 5

A shirt is priced at $40 and is sold for $28. What is the discount percentage?

  1. 20%
  2. 30% (correct answer)
  3. 25%
  4. 15%
Explanation: This question asks for the discount percentage when a $40 shirt is sold for $28. Percent decrease is $(original - sale price) \div original \times 100.Here:. Here: (40 - 28) \div 40 \times 100 = 12 \div 40 \times 100 = 0.30 \times 100 = 30%$. Choice C incorrectly calculated 25%, possibly using the wrong denominator or making an arithmetic error.

Question 6

A test has 4040 questions, and a student answers 3030 correctly. What percent of the questions did the student answer correctly?

  1. 25%25\%
  2. 75%75\% (correct answer)
  3. 13313%133\frac{1}{3}\%
  4. 30%30\%
Explanation: We need to find what percent 30 correct answers is out of 40 total questions. To find what percent one number is of another, use (part/whole) × 100. Here: (30/40) × 100 = 0.75 × 100 = 75%. Choice A (25%) incorrectly uses the difference (10/40) instead of the part over the whole.

Question 7

A sweater is discounted 20%20\% from its original price of $65. What is the discounted price?

  1. $52 (correct answer)
  2. $45
  3. $78
  4. $13
Explanation: We need to find the discounted price of a $65 sweater with a 20% discount. First find the discount amount: 20% of $65 = 0.20 × $65 = $13. Then subtract from the original price: $65 - $13 = 52.ChoiceD(52. Choice D (13) is just the discount amount, not the final price.

Question 8

If 120%120\% of a number is 360, what is 40%40\% of that number?

  1. 120 (correct answer)
  2. 144
  3. 300
  4. 480
Explanation: This is a two-step percentage question. Choice A (120) is correct — first find the base number: 1.20 × x = 360 → x = 300. Then find 40%: 0.40 × 300 = 120. Choice B (144) skips finding the base number and takes 40% of 360 directly: 0.40 × 360 = 144. This confuses the given quantity (360) with the base number (300). Choice C (300) correctly finds the base number but stops there — reporting the intermediate result instead of answering the actual question, which asks for 40% of that number. Choice D (480) applies the wrong percentage, possibly computing 160% of 300 = 480. Pro tip: Multi-step percent problems require full execution. Read the question carefully at the end — here it asks for 40% of the original number, not for the original number itself. Finding 300 is the setup, not the finish.

Question 9

A retail store discounts an item by 2020\\% during a sale. At the cash register, a 1010\\% sales tax is applied to the discounted price.

If the final amount paid by the customer is \\88.00$, what was the original price of the item before the discount?

  1. $80.00
  2. $96.00
  3. $100.00 (correct answer)
  4. $120.00
Explanation: This is a multi-step percentage question testing sequential operations. Choice C ($100.00) is correct — let P = original price. After 20% discount: P × 0.80. After 10% tax on the discounted price: P × 0.80 × 1.10 = P × 0.88. Set equal to $88: P × 0.88 = 88 → P = 100.ChoiceA(100. Choice A (80.00) undoes only the tax but not the discount: $88 ÷ 1.10 = 80—findingthepre−taxdiscountedpriceratherthantheoriginalprice.ChoiceB(80 — finding the pre-tax discounted price rather than the original price. Choice B (96.00) undoes only the discount but not the tax: $88 ÷ 0.80 = $110... wait — that gives $110. $96 may come from 88+1088 + 10% − 2% \= various errors. Choice D (120.00) applies a single combined reversal incorrectly, possibly computing $88 ÷ 0.80 + tax error. Pro tip: Work backwards through sequential percentage changes. The final price $88 = original × 0.80 × 1.10. To find the original, divide by BOTH factors: $88 ÷ (0.80 × 1.10) = $88 ÷ 0.88 = $100. Never undo just one of the percentage operations.

Question 10

If 3030\\% of a given number is 6060, what is 5050\\% of that same number?

  1. 80
  2. 90
  3. 100 (correct answer)
  4. 120
Explanation: The correct answer is C (100). First find the original number: if 30% of x = 60, then x = 60 ÷ 0.30 = 200. Then find 50% of that number: 0.50 × 200 = 100. A (80) likely comes from an unclear arithmetic path, possibly computing 60 + 20. B (90) results from estimating or making an error when computing the ratio 50/30 × 60. D (120) is the most common trap — doubling the given value (60 × 2 = 120) instead of first finding the base number. The key insight is that you must find the whole (200) before computing the new percentage.

Question 11

What is 60% of 75?

  1. 55
  2. 50
  3. 40
  4. 45 (correct answer)
Explanation: This question asks us to find 60% of 75. To find a percent of a number, convert the percent to a decimal and multiply: 60%=0.6060\% = 0.60. Calculate: 0.60×75=450.60 \times 75 = 45. Choice B (50) might result from incorrectly calculating 2/3 of 75 or making an arithmetic error.

Question 12

What is 15%15\% of 200200?

  1. 33
  2. 3030 (correct answer)
  3. 30003000
  4. 1515
Explanation: We need to find 15%15\% of 200. To find a percent of a number, convert the percent to a decimal and multiply: 15%=0.1515\% = 0.15, so 0.15×200=300.15 \times 200 = 30. Choice A (33) incorrectly omits a zero, and choice C (30003000) incorrectly multiplies by 15 instead of 0.15.

Question 13

What is 50% of 90?

  1. 45 (correct answer)
  2. 40
  3. 50
  4. 55
Explanation: This question asks for 50% of 90. To find a percent of a number, convert the percent to a decimal and multiply. 50%=0.5050\% = 0.50, so 0.50×90=450.50 \times 90 = 45. Choice B incorrectly calculated approximately 44% of 90, while choice C used 55% instead of 50%.

Question 14

What percent of 500 is 125?

  1. 15%
  2. 20%
  3. 25% (correct answer)
  4. 30%
Explanation: This question asks what percent 125 is of 500. To find what percent one number is of another, use (part ÷ whole) × 100. Here: (125 ÷ 500) × 100 = 0.25 × 100 = 25%. Choice B incorrectly calculated 20%, while choice A gave 15%, both showing computational errors in the division.

Question 15

Convert 0.25 to a fraction.

  1. 14\frac{1}{4} (correct answer)
  2. 12\frac{1}{2}
  3. 13\frac{1}{3}
  4. 25\frac{2}{5}
Explanation: This question asks to convert the decimal 0.25 to a fraction. 0.25=251000.25 = \frac{25}{100}, which simplifies by dividing both numerator and denominator by 25: 25÷25=125 \div 25 = 1 and 100÷25=4100 \div 25 = 4, giving 14\frac{1}{4}. Choice B incorrectly gives 12\frac{1}{2}, which equals 0.500.50, not 0.250.25.

Question 16

What is 30%30\% of 9090?

  1. 6363
  2. 33
  3. 270270
  4. 2727 (correct answer)
Explanation: We need to find 30% of 90. To find a percent of a number, convert the percent to a decimal and multiply: 30% = 0.30, so 0.30 × 90 = 27. Choice B (3) incorrectly divides by 30 instead of multiplying by 0.30, and choice C (270) incorrectly multiplies by 30 instead of 0.30.

Question 17

What percent of 8080 is 2020?

  1. 4%4\%
  2. 25%25\% (correct answer)
  3. 60%60\%
  4. 400%400\%
Explanation: We need to find what percent 20 is of 80. To find what percent one number is of another, use (part/whole) × 100. Here: (20/80) × 100 = 0.25 × 100 = 25%. Choice A (4%) incorrectly uses 20/500, and choice C (60%) incorrectly calculates 80-20 as a percent.

Question 18

What is the percent decrease from 150 to 120?

  1. 25%
  2. 15%
  3. 20% (correct answer)
  4. 30%
Explanation: This question asks for the percent decrease from 150 to 120. Percent change is (new value - original value)/original value × 100. Calculate: (120 - 150)/150 × 100 = -30/150 × 100 = -0.20 × 100 = -20%, so the decrease is 20%. Choice B (15%) might result from using 120 as the denominator instead of 150.

Question 19

An item costs $80 and is marked up by 25%. What is the new price?

  1. $100 (correct answer)
  2. $90
  3. $95
  4. $85
Explanation: This question asks for the new price of an $80 item marked up by 25%. Calculate the markup: 25% of $80 = 0.25 × $80 = $20. Add to the original price: $80 + $20 = 100.ChoiceC(100. Choice C (95) might result from calculating an 18.75% markup instead of 25%.

Question 20

A town's population increased from 12,00012{,}000 to 15,00015{,}000 over one year. What was the percent increase, based on the original population?

  1. 20%20\%
  2. 25%25\% (correct answer)
  3. 3%3\%
  4. 80%80\%
Explanation: This problem asks for the percent increase from 12,000 to 15,000 people. Percent change is calculated as (new value - original value)/original value × 100. Here, (15,000 - 12,000)/12,000 × 100 = 3,000/12,000 × 100 = 0.25 × 100 = 25%. Choice A (20%) might result from incorrectly using the new value as the denominator instead of the original value.