Question

A truck driver traveled at an average speed of 63 miles per hour on a 200 mile trip to pick up a load of freight. On the return trip(with the truck fully loaded). the average speed was 40 miles per hour. Find the average speed for the round trip. (round your answer to one decimal place)

Answer 1

Remark

One thing you have to understand from the beginning. The average speed is not (63 + 40) / 2 = 103/2 = 51.5

Formula

Average speed = Total Distance / Total Time.

Note:

That means you have to made 2 calculations, there and back.

Step One

Calculate the time for going to to his destination.

d = 200 miles

r = 63 miles

t = ??

d = r*t

200 = 63 * t

t = 200/63

t = 3.175

Step Two

Calculate the time for coming back.

d = 200 miles

r = 40 miles / hour

t = ??

d = r * t

200 = 40 * t

t = 200 / 40

t = 5 hours.

Step Three

Find the average speed.

d = 200 miles + 200 miles = 400 miles

t = 5 hours + 3.175 hours = 7.175 hours.

r = ??

d = r * t

400 = r * 8.175

r = 400/8.175

r = 48.93 miles / hour Answer