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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Steve traveled the first 2 hours of his journey at 40 mph...
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BTGmoderatorLU
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DavidG@VeritasPrep
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Total time = 2 + 3 = 5 hours.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.
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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ceilidh.erickson
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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.
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.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
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Jeff@TargetTestPrep
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Steve's total distance was 2 x 40 + 3 x 80 = 80 + 240 = 320 miles.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
We can now determine average speed:
Average speed = (total distance)/(total time)
Average speed = 320/5 = 64 mph.
Answer: D
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