Problem-Solving and Data Analysis · Math

Percentages

Percentages: finding a percent of a number, percent change, reversing a percent change, and successive changes.

18 questions in the bank · 4 easier · 5 medium · 9 harder · this domain is ≈15% of the section

Learn it in the Guide

What to watch for

Percent changes compound rather than add: a 20% rise followed by a 20% fall does not return to the original, because the second percent acts on a different base.

How the question is worded

These are the actual stems used in the bank — the SAT reuses a small set of wordings, and recognising them saves time on test day.

  • What is 30% of 200?
  • What is 20% of 40?
  • What is 35% of 120?
  • What is 40% of 80?

Worked examples

easyWhat is 30% of 200?

What is 30% of 200?

  • A. 60
  • B. 140
  • C. 260
  • D. 6000

Answer: A. 60

Explanation

30% means 30/100. Multiply: (30/100) × 200 = 60. Converting the percent to a decimal or fraction first keeps the arithmetic honest.

mediumThe number of members in a club decreased by 30% from last year's 40 members. …

The number of members in a club decreased by 30% from last year's 40 members. How many members does the club have this year?

  • A. 10
  • B. 12
  • C. 28
  • D. 52

Answer: C. 28

Explanation

A 30% decrease multiplies the original by 1 − 0.3 = 0.7: 40 × 0.7 = 28. Adding 30 as a raw number is the classic percent trap.

hardAfter a 25% increase, the price of an item is $100. What was the price, in dol…

After a 25% increase, the price of an item is $100. What was the price, in dollars, before the increase? (Disregard the $ sign when entering your answer.)

Answer: 80

Explanation

“After a 25% increase” means the new price is 125% of the original: 1.25x = 100, so x = 100/1.25 = 80. Taking 25% OF THE NEW PRICE and subtracting is the error this question is built to catch — the percent was applied to the original, not the new amount.