GMAC paper test #6

by **1week2go** Mon Sep 17, 2007 3:44 pm

I have another rate problem....

In the first of a two hour trip, a car traveled d kilometers, and in the second hour of the trip, the car traveled one-half that distance. What is the average rate at which the car traveled during the trip, in kilometers per hour?

a) d
b) 1/3(d)
c) 1/2(d)
d) 3/4(d)
e) 3/2(d)

Would I use the VIC strategy?

by **Guest** Mon Sep 17, 2007 4:54 pm

Total distance travelled = (d+d/2)
Total time = 2 hrs

Avg speed (d+d/2)/(2) = (3/4)d

by **RonPurewal** Tue Sep 18, 2007 4:02 am

This is an absolutely classic "VIC" problem.

Pick a number for 'd'. Noting the fractions in the answer choices, you might want to pick a 'd' that's a multiple of 2, 3, and 4, so that all the answer choices will be integers.

Let's let d = 12. Then the car goes 12km in the first hour, and 6km in the second hour.
This is a total of 18km in two hours, so the average rate is 18/2 = 9 km/h.

Since 'd' is 12, the answer is D.