Week 7: Percent Increase/ Decrease

Directions: For each problem, find the percent increase or decrease by making a fraction and turning it into a percent.

Sample Question: A company made $40,000 in the first quarter of the year. In the second quarter, the company made $50,000. By what percent did the company's earnings increase?

Answer: Their earnings increased 25%.

Explanation: One way to solve this problem is by using the formula To find the change, simply subtract the two numbers. The original number was the number before the increase or decrease took place. In this case the fraction is We turn this into a decimal, 0.25. To make it a percent, move the decimal 2 spaces to the right (25%.)

1. In September, 50 students were absent from school. In October, 55 students were absent. By what percent did the number of absences increase?

2. In July, there were 15 accidents on Lakeside Blvd. In August, there were 12 accidents on the same road. By what percent did the number of accidents decrease?

3. An author completed 10 chapters of his book in the first month. In the second month, he completed 5 chapters. By what percent did his chapter completion decrease?

4. At an engine shop, a racecar engine was producing 700 horsepower. The race team wanted to boost the horsepower to 750. What was the percent gain in horsepower they were looking for?

5. At a gas station, the price of gas had been $2.50. After the hurricances, the prices rose to $3.00. What was the percent increase in price?