It is a sunny day in California and both male and female students are out surfing. There are 70 surfers, including 25 females. What percent of surfers are female? Write a proportion for this situation and solve. Round to the nearest tenth.

Work Shown:

We'll use the idea that something like 25% means 25/100

So in general x% = x/100, where x is any positive number.

From here we can say the following:

(number of females)/(number of surfers) = (percent)/100

25/70 = x/100

25*100 = 70*x ... cross multiply

2500 = 70x

70x = 2500

x = 2500/70 ... divide both sides by 70

x = 35.7142857142858 ... which is approximate

x = 35.7

Roughly 35.7% of the surfers are female.

Note how 25/70 = 0.357 approximately; afterward you move the decimal point 2 spots to the right to get to 35.7%