Question

On a certain Monday, Carlos drove to work at an average speed of 50 miles per hour and home from work along exactly the same route at an average speed of 70 miles per hour. Which of the following is closest to his average speed for both trips combined?A. 58.3 miles per hourB. 60.0 miles per hourC. 62.6 miles per hourD. 65.4 miles per hourE. It cannot be determined from the information given

Answer 1

A. 58.3 miles per hour

Explanation:

Average speed can be calculated using the formula
`(D)/(t)` where

• D is the total distance traveled.
• t is the total time spend during the travel.

Let X be the distance home to Carlos' work. Then total distance traveled is 2X since Carlos drove to work and then to home.

The time spend while driving from home to work is :
`(X)/(50)`

The time spend while driving from work to home is :
`(X)/(70)`

Thus, total time spend is
`(X)/(50)` +
`(X)/(70)` =
`(12X)/(350)`

And finally, average speed is
`(2X)/((12X)/(350) )` = 58.33 miles per hour