Average US gas price is $___ per gallon, a __% increase

• A. 3.50,18
• B. 3.70,26
• C. 4.00,30
• D. 3.90,22

Answer: (B)

Percent increase is how much the price rose from what it was before. To check a pair, use the idea that the current price equals the old price multiplied by 1 plus the increase (as a decimal). So if the current price is 3.70 and the increase is 26%, the previous price would be 3.70 / 1.26 ≈ 2.94. The actual rise is 3.70 − 2.94 ≈ 0.76, and 0.76 is about 26% of 2.94 (0.76 / 2.94 ≈ 0.258 ≈ 26%). This shows the numbers are consistent with the way a percentage increase is reported. The key skill is converting the percentage back to a previous price to verify the change.