miles per hour

Question

It takes Kelly 5 hours to drive 500 kilometers to her grandmother's house. If she makes the return trip in 4 hours and 20 minutes, how fast did she drive per hour on the way home?

I get ~115.5 mph but am told the answer is 120 mph

 

Thank you!

Answer 1

First, we should check the answers.

115.5(4 1/3)      20 min = 1/3 hour

115.5(13/3)

500.5 (not 500)

 

120(13/3)

520  (like wise not 500)

 

d = r · t

d / t = r

 

500 / (4 1/3) = r

500 / 13/3 = r

500(3/13) = r        divide by fraction multiply by inverse

115.38 = r

 

You are a lot closer than 120!