Example

Finding the Percent Decrease in Average Gas Prices

Apply the seven-step problem-solving strategy to find a percent decrease.

Problem: The average price of a gallon of gas in one city in June 2014 was $3.71. The average price in that city in July was $3.64. Find the percent decrease.

  1. Identify what to find: the percent decrease.
  2. Name the unknown: Let pp = the percent decrease.
  3. Find the amount of decrease: Subtract the new price from the original price:

3.713.64=0.073.71 - 3.64 = 0.07

  1. Translate the percent question: "0.070.07 is what percent of 3.713.71?" becomes the equation:

0.07=p×3.710.07 = p \times 3.71

  1. Solve by dividing both sides by 3.713.71:

0.073.71=p\frac{0.07}{3.71} = p

p0.019p \approx 0.019

  1. Convert to percent form and round to the nearest tenth:

p1.9%p \approx 1.9\%

  1. Check: If the original price had been $4, then 2%2\% of $4 would be 8 cents. Since $0.07 is close to 8 cents and $3.71 is close to $4, a result of 1.9%1.9\% is reasonable.
  2. Answer: The price of gas decreased 1.9%1.9\%.

This example shows the percent decrease procedure in action with decimal values. In Step 3 the original amount is placed first in the subtraction (originalnew\text{original} - \text{new}) so the result is positive, and in Step 5 the division is rounded to the nearest thousandth (0.0190.019) in order to express the final percent to the nearest tenth (1.9%1.9\%).

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Updated 2026-04-21

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