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

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Answer 1 · 2016-08-15T11:50:41

$27.27 %$ $27.27%$

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

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

$55 x = 70 \times 100$ $55x = 70 xx100$

$x = \frac{70 \times 100}{55}$ $x = (70 xx100)/55$

$x = 127.27$ $x = 127.27$

The percent increase is therefore 127.27-100 = 27.27%

This can be checked by the method:

$\frac{change}{original} \times 100 %$ $("change")/("original") xx 100%$

$\frac{15}{55} \times 100 % = 27.27 %$ $15/55 xx100% = 27.27%$