At 10 a. m., there were 12 people in a swimming pool. At 11 a. m., there were 27 people in the pool.

What was the percent of increase in the number of people in the swimming pool from 10 a. m. to 11 a. m.?

So assumng 12=100 percent

12=100

27=x%

subtract

27-12=15

find what percent of 12=15

15> 12 so 15 is >100% of 12

remember that there is a 100% there

15-12=3

find what percent 3 is of 12

3/12=1/4=25%

so 25+100=125

27 is 125% more than 12