Question

If Herschel walker can sprint 40 meters in 4.35 seconds, how many miles per hour is he running? Round to the nearest tenth

A) 4.7 mi/hr
B) 20.6 mi/hr
C) 17.9 mi/hr
D) 5.5 mi/hr

Answer 1

B) 20.6 mi/hr

Explanation:

To solve this, we need to first convert 40 meters to mile, then convert 4.35 seconds to hour, then solve by proportion.

converting 40 meters to mile;

1 mile = 1609.344 meter

x = 40 meters

1609.344x = 40

x = 40/1609.344

x =0.02485 mile

Then converting seconds to hour

1 hour = 3600 seconds

y = 4.35 seconds

3600 y = 4.35

y=4.35/3600

y =0.00121 hour

Using proportion to solve the question

Let n be the number he runs miles per hour

0.02485 mile = 0.00121 hour

n = 1 hour

cross-multiply

0.00121 n = 0.02485

Divide both-side by 0.00121

0.00121 n/0.00121 = 0.02485/0.00121

n ≈ 20.6 mile/hour

Therefore, he is running 20.6 mi/hr