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Percents and percent change — ACT practice questions

Practice 43 Percents and percent change questions in the app

What this topic is

On the ACT Mathematics test, Percents and percent change covers finding a percent of a quantity, recovering a whole from a given percent, and measuring a rise or fall against a starting amount.

Students must convert percents to decimals, divide change by the original, and handle a price that increases by 20% then decreases by 20% without treating the moves as canceling. Items are multiple choice with five options, often percents or whole counts.

Common traps include dividing by the new figure, reversing part and whole, and assuming the final price matches the original.

Sample questions

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Question 1Easier

A survey received 224 responses, which is 44.8%44.8\% of the people invited. How many people were invited?

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Answer: C — 500

If TT people were invited, then 0.448T=2240.448T=224. Dividing gives T=500T=500 people.

Question 2Easier

A workshop produced 200 lamps in its first month and 160 lamps in its second month. What was the percent change from the first month to the second?

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Answer: B — 20%20\% decrease

Production decreased by 200160=40200-160=40 lamps. Relative to the original 200, the change is 40200=0.20\dfrac{40}{200}=0.20, or a 20%20\% decrease.

Question 3Easier

A jacket’s price increases by 20%20\%, then the new price decreases by 20%20\%. The final price is what percent of the original price?

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Answer: B — 96%96\%

Multiplicative change: 1.2×0.8=0.961.2\times 0.8=0.96, so the final price is 96%96\% of the original.

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Practice 43 Percents and percent change questions in the app

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