Robin drove from Townville to Villageton. Upon arriving in Villageton,

Question

Robin drove from Townville to Villageton. Upon arriving in Villageton, she immediately returned to Townville. What was Robin’s average speed for the entire trip?

(1) While driving from Townville to Villageton, Robin’s average speed was 40 miles per hour. While driving from Villageton to Townville, Robin’s average speed was 60 miles per hour.

(2) The distance from Townville to Villageton is 120 miles.

Kudos for a correct  solution .

Gnpth · Answer

St--1:

The average distance =  \frac{Total distance}{total time}

Let D be the distance, then

Average Speed =  \frac{2D}{ }

=  \frac{(2*40*60)}{100}  =  \frac{4800}{100} = 48 Miles Per hour.

Sufficient.

St-2: No Individual speed or time is given. So not sufficient.

Answer : A.

Celerma · Answer

Statement A : v=2d/(t1+t2) , v=2d/(d/40+d/60) sufficient.
Statement B : Clearly insufficient. So the answer is A.

peachfuzz · Answer

Statement 1 :
r=rate
d=distance
r ((d/40) + (d/60)) = 2d
r = 48
Sufficient

Statement 2 :
distance one way is 120, no times or rates are given
Insufficient

Answer : A

Lucky2783 · Answer

Answer A.

Option 1: Avg. Speed =  \frac{2*40*60}{40+60} 
option 2: we just know the distance , D=S*T we need to know 2 values in order to determine the 3rd in distance equation.

Bunuel · Answer

MAGOOSH OFFICIAL SOLUTION: robinsaveragespeed_text.PNG

lalania1 · Answer

Quick question here.

In stmt1, can I use a smart number for D, let's say D=120?. that way I could solve the question much faster. However, I dont want to do something wrong such as an approach that is not correct. Please confirm whether I can use a number for D in order to solve this question using numbers.

vroldao · Answer

I've got one concern - nothing is said in the question whether she took the same course both ways. It could be the case she took different roads, of different lengths. In that case 1) would not be enough.
It's a valid question, no?
What should one do if faced with such problem during the actual exam?

jppresa · Answer

Bunuel  shouldn't the question specify that the same route was taken on both journeys?

Robin drove from Townville to Villageton. Upon arriving in Villageton,

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GMAT Data Sufficiency (DS) Questions

Robin drove from Townville to Villageton. Upon arriving in Villageton,

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