Bunuel wrote:

In the first hour 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

Solution:

Lets look at the information given in the question...

Total time travelled = 2 hrs

Distance travelled first hour = d

Distance travelled second hour = d/2

The question is asking for the avg speed at which the car travels for 2 hrs

We know that avg speed = total distance/total time

Lets place the information given in the question to the formula above = (d+d/2)/2

= 3/4*d

We find that option D is the answer as it gives the same expression as found in our calculation above. Answer option D.