Bunuel wrote:
Jim travels the first 3 hours of his journey at 60 mph speed and the remaining 5 hours at 24 mph speed. What is the average speed of Jim's travel in mph?
A. 36 mph
B. 37.5 mph
C. 42 mph
D. 42.5 mph
E. 48 mph
The question has been answered nicely already, so I won't get into that.
However,
if you're not sure how to proceed with the questions or you're pressed for time, you can get to a 50-50 guessing situation in about 10 seconds.
IF Jim traveled at 60 mph for the SAME amount of time that he traveled at 24 mph, then the average speed would be the average of 60 and 24.
That is, if he had spent the same time driving at each speed, his average speed WOULD HAVE been
42 mph, since (60+24)/2 = 42
HOWEVER, since Jim actually spent MORE TIME driving at 24mph, his average speed will be closer to 24mph than to 60mph.
In other words, his average speed will be LESS THAN
42 mph
This means the correct answer is either A or B.
Guess and move on.
Cheers,
Brent
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