Question

A cyclist rides his bike at a speed of 22 feet per second. what is this speed in miles per hour? how many miles will the cyclist travel in 4 hours? in your computations, use the fact that 1 mile is equal to 5280 feet. do not round your answers.

Answer 1

1 second = 22 feet

Find 1 minute:
1 min = 22 x 60 = 1320 feet                [1 minute = 60 seconds]

Find 1 hour:
1 hour = 1320 x 60 = 79200 feet         [1 hour = 60 minutes]

Find in miles:
1 hour =  79200 ÷  5280 = 15 miles     [1 mile =  5280 feet]

Answer: speed = 15 miles/hour

1hour = 15 miles

4 hours = 15 x 4 = 60 miles

Answer: 60 miles

Answer 2

First we set up proportions to find out how many miles per hour the cyclists rides his bike at. 

Let ft = feet, sec = second(s), min = minute(s), hr = hour(s), mi = mile(s)

$\frac{22 ft}{sec} * \frac{60 sec}{min} * \frac{60 min}{hr} * \frac{1 mi}{5280 ft}$

Translation of all that: The cyclist goes 22 feet per second. There are 60 seconds in a minutes and 60 minutes in an hour. 1 mile is equal to 5280 feet. Multiply these fractions all together; everything will cancel except for miles divided by hours AKA miles per hour. 

22 * 60 * 60 * 1 = 79200
79200 / 5280 = 15

He is going 15 miles per hour. So he will go 60 miles in 4 hours.