Question

Jon walked 80 feet in 14.3 seconds what is his speed in miles per hour?

Answer 1

Conversion

Since the information is given in feet and seconds, and we want the answer in miles and hours, we make a conversion:

Miles

We want to find how many miles correspond to 80 feet if 1 mile is 5280 feet. We have the following equivalence

? miles ↔ 80 feet

1 miles ↔ 5280 feet

If we divide both side of the equivalence we will have the same result:

$\begin{gathered} \frac{?}{1}=\frac{80}{5280} \\ \downarrow \\ ?=\frac{8}{528} \\ \text{?=}\frac{1}{66}\cong0.015 \end{gathered}$

Then, 80 feet are 0.015 miles

Hours

We want to find how many hours correspond to 14.3 second if 1 hour is 3600 seconds. We have the following equivalence

? hours ↔ 14.3 seconds

1 hours ↔ 3600 seconds

If we divide both side of the equivalence we will have the same result:

$\begin{gathered} \frac{?}{1}=\frac{14.3}{3600} \\ \downarrow \\ ?=0.00397\cong0.004 \end{gathered}$

Then, 14.3 seconds are 0.004 hours

Speed

We find the speed by dividing both values:

speed = miles / hour

then,

$\frac{0.015}{0.004}=3.7878\cong3.8$

Answer- the speed is 3.8 miles per hour