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Steve traveled the first 2 hours of his journey at 40 mph...

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Steve traveled the first 2 hours of his journey at 40 mph...

by BTGmoderatorLU » Tue Oct 24, 2017 4:13 pm
Steve traveled the first 2 hours of his journey at 40 mph and the last 3 hours of his journey at 80 mph. What is his average speed of travel for the entire journey?

A. 53.33 mph
B. 56.67 mph
C. 60 mph
D. 64 mph
E. 66.67 mph

The OA is D.

I need help with this PS question. Can any expert explain it please? Thanks.
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by DavidG@VeritasPrep » Wed Oct 25, 2017 7:02 am
LUANDATO wrote:Steve traveled the first 2 hours of his journey at 40 mph and the last 3 hours of his journey at 80 mph. What is his average speed of travel for the entire journey?

A. 53.33 mph
B. 56.67 mph
C. 60 mph
D. 64 mph
E. 66.67 mph

The OA is D.

I need help with this PS question. Can any expert explain it please? Thanks.
Total time = 2 + 3 = 5 hours.

Next, find the total distance
First part of trip: 2*40 = 80 miles
Second part of trip 3*80 = 240 miles
Total Distance = 80 + 240 = 320 miles.

Average Speed = Total Distance/Total Time = 320/5 = 64 The answer is D. .
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by ceilidh.erickson » Wed Oct 25, 2017 2:57 pm
David's explanation is perfect. It helps to remember on any of these questions that average rate is a WEIGHTED AVERAGE. If there are two legs of the journey at different rates, the overall rate will be weighted toward the one you spent more TIME doing.

In this problem, the simple average of 40mph and 80mph would be 60. Since Steve spent more time going 80mph, though, the right answer must be more than 60. Knowing that, we can quickly eliminate A, B, and C. If you then got stuck on solving, you'd have a 50/50 shot at guessing correctly between D and E.
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by Jeff@TargetTestPrep » Sun Oct 29, 2017 6:27 am
LUANDATO wrote:Steve traveled the first 2 hours of his journey at 40 mph and the last 3 hours of his journey at 80 mph. What is his average speed of travel for the entire journey?

A. 53.33 mph
B. 56.67 mph
C. 60 mph
D. 64 mph
E. 66.67 mph
Steve's total distance was 2 x 40 + 3 x 80 = 80 + 240 = 320 miles.

We can now determine average speed:

Average speed = (total distance)/(total time)

Average speed = 320/5 = 64 mph.

Answer: D

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