A driver completed the first 20 miles of a 40-mile trip at an average speed of 50 miles per hour. At what average speed must the driver complete the remaining 20 miles to achieve an average speed of 60 miles per hour for the entire 40-mile trip? (Assume that the driver did not make any stops during the 40-mile trip.)

A. 65 mph

B. 68 mph

C. 70 mph

D. 75 mph

E. 80 mph

Question

Mathematics

Reina Carr

15 February, 10:37

A driver completed the first 20 miles of a 40-mile trip at an average speed of 50 miles per hour. At what average speed must the driver complete the remaining 20 miles to achieve an average speed of 60 miles per hour for the entire 40-mile trip? (Assume that the driver did not make any stops during the 40-mile trip.)

A. 65 mph

B. 68 mph

C. 70 mph

D. 75 mph

E. 80 mph

+3

Answers (1)

Know the Answer?

Joseph Blackburn · Answer 1

Step-by-step explanation:

D

I am not sure if I did this the easiest way, but here's how I went about it.

40 miles/60 mph = average trip time

20 miles/50 mph = time it took to complete first 20 miles

20 miles/X mph = time it took to complete second 20 miles

therefore

40/60 hours = 20miles/50mph + 20miles/X mph.

Solved for X and you get 75