ms.Lewis plans to drive 900 miles to her vacation destination, driving an average of 50 miles per hour. How many miles per hour faster must she average, while driving to reduce her total driving time by 3 hours?

A. 5
B. 8
C. 10
D. 15
E. 18

Question

ms.Lewis plans to drive 900 miles to her vacation destination, driving an average of 50 miles per hour. How many miles per hour faster must she average, while driving to reduce her total driving time by 3 hours?

A. 5
B. 8
C. 10
D. 15
E. 18

zpupster · Answer

distance = rate*time
900=50*t
900/50=t
this is the time it takes her at 50mph, so take this t and subtract 3 and place back in formula
900=r*t
900/t=r
r= the rate it takes at 3 hours less
lastly take the r here
r-50=rate it will take to cut driving time by 3 hours