On New Year's Eve, a limousine driver traveled from Philadelphia to Pi

Question

On New Year's Eve, a limousine driver traveled from Philadelphia to Pittsburgh at an average rate of 75 miles per hour. On his return trip to Philadelphia, he encountered a heavy snow storm, which reduced his speed to 45 miles per hour. What was the limousine driver's average speed for the entire trip, in miles per hour?

A. 55
B. 56
C. 58
D. 60
E. 62

A. 55
B. 56
C. 58
D. 60
E. 62

Archit3110 · Answer

since distance is same
so avg speed = 2 *a*b/( a+b) 
=> 2*45*75 /120 ; 56
OPTION B

stne · Answer

Avg. Speed =  \frac{2*75*45}{75+45}= 56.25

So closest answer 56
Ans- B

GMATinsight · Answer

CONCEPT :  AVerage-Speed = \frac{Total-Distance}{Total-Time}

For same distance travelled forward and backward,  AVerage-Speed = \frac{2*a*b*}{a+b}

a = 75 and b = 45

Average Speed = \frac{2*75*45}{75+45} = \frac{150*45}{120} = 56.25

Answer: Option B

chrtpmdr · Answer

How did you come up with that formula?

MathRevolution · Answer

Average speed =  \frac{2*a*b }{ a+b}

=>  \frac{2*75*45}{75+45}

=>  \frac{2*75*45}{120}

=> 56.25

Answer B

violinix · Answer

I'm sorry, but this seems like a bad question. The result (56.25 mph) is not represented in any answer. Answer B is the closest, but the question does not ask for closest or an estimation.

MustafaChang · Answer

i dont get this. how is the total time 45+75??

On New Year's Eve, a limousine driver traveled from Philadelphia to Pi

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