anilnandyala wrote:
Susan drove an average speed of 30 miles per hour for the first 30 miles of a trip & then at a average speed of 60 miles/hr for the remaining 30 miles of the trip if she made no stops during the trip what was susan's avg speed in miles/hr for the entire trip
A. 35
B. 40
C. 45
D. 50
E. 55
Average speed = (TOTAL distance)/(TOTAL time)TOTAL distanceSusan traveled 30 miles at a speed of 30mph, and 30 miles more at a speed of 60mph.
So, TOTAL distance = 30 miles + 30 miles =
60 miles TOTAL timeTOTAL time = (time spent driving 30 mph) + (time spent driving 60 mph)
time = distance/speed
- Time spent driving 30 mph = 30 miles/30mph =
1 hour
- Time spent driving 60 mph = 30 miles/60mph =
0.5 hours
TOTAL time = (
1 hour) + (
0.5 hours) =
1.5 hours----------------------------------
So, Average speed = (
TOTAL distance)/(
TOTAL time)
=
60 miles/
1.5 hours= 40 mph
Answer: B
Cheers,
Brent
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