Question

Stan drove for h hours at a constant rate of r miles per hour. How many miles did he cover during the final 20 minutes of his drive?

Answer 1

20 minutes is
`(1)/(3)` of an hour (60 minutes).

Stan's constant rate is r miles per hour, which means he drove r miles in 60 minutes. So how many miles did he drive in 20 minutes? As explained in the first line, 20 minutes is
`(1)/(3)` of an hour. Since his rate is constant, Stan would drive
`(1)/(3)` of what he cover in 60 minutes, which is r miles.

Hence, Stan drove
`(1)/(3)r` miles in 20 minutes.

ANSWER:
`(1)/(3)r` miles