GmatPrep

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GmatPrep

by dubeystuts » Sun Feb 01, 2009 3:40 am
P, Q and R are located in a flat region of a certain state. Q is x miles due east of P and y miles due north of R. Each pair of points is connected by a straight road. What is the number of hours needed to drive from Q to R and then from R to P at a constant rate of z miles per hour, in terms of x, y and z? (Assume x,y and z are positive)

1) sqr root x^2 +y^2 / z
2) x + sqr root x^2 +y^2 / z
3) y + sqr root x^2 +y^2 / z
4) z / x + sqr root x^2 +y^2
5) z / y + sqr root x^2 +y^2

Can someone please explain how to answer this question? The right answer is C. Many thanks for your help.
Source: — Problem Solving |

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by DeepakR » Sun Feb 01, 2009 3:50 am
PQR will form a right triangle with PQ=x and QR=y hence PR= sqrt(x^2+y^2) now the total time taken T= (Distance between QR/Speed ) + (Distance between PR/Speed )

We know that distance b/w QR =y and distance between PR=sqrt(x^2+y^2)
Hence T=[y+sqrt(x^2+y^2)]/z = Ans C.)

- Deepak

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by dubeystuts » Sun Feb 01, 2009 2:45 pm
Many thanks Deepak.