# How do you find the percent increase using proportions given 55 mph to 70 mph?

Aug 15, 2016

27.27%

#### Explanation:

The original starting speed of 55mph represents 100%, while the speed of 70mph is the speed increased by a certain percent

$\frac{55}{100} = \frac{70}{x}$

$55 x = 70 \times 100$

$x = \frac{70 \times 100}{55}$

$x = 127.27$

The percent increase is therefore 127.27-100 = 27.27%

This can be checked by the method:

("change")/("original") xx 100%

15/55 xx100% = 27.27%