Question

In reducing one's speed from 70 mph to 50 mph, how much of a percentage decrease in stopping distance is realized (to the nearest percent)?

Answer 1

we are given relation between speed and distance

distance ( when speed =70mph) is

=328feet

so, $d_1=328$

distance ( when speed =50mph) is

=183feet

so, $d_2=183$

now, we can find percentage in decrease

$=\frac{d_1-d_2}{d_1}\times 100$

now, we can plug values

$=\frac{328-183}{328}\times 100$

$=44$%...........Answer