Monday, December 12, 2011

Speed Distance Time : TANCET Quant

Speed Distance Time is one of the topics from which you should expect a question either in the quantitative reasoning section or in the data sufficiency section of the TANCET MBA.

Here is a relatively easy quantitative reasoning question from this topic

It takes Kiran 50 minutes lesser to cover a distance if she travels three times as fast as she does now. How long will she take to cover the distance if she travels twice as fast as she does now?
1. 50 minutes
2. 75 minutes
3. 150 minutes
4. 100 minutes
5. 37.5 minutes

Correct Answer : Choice 5. 37.5 minutes

Explanatory Answer

Let Kiran's present speed be S km/min. And let her take t minutes to reach her destination.

If Kiran travels three times as fast as she does now i.e., at 3S, she will cover the same distance in 1/3 of the time i.e., in t/3 minutes.

So, she is saving (t - t/3) minutes = 2t/3 minutes.
The question states that she is saving 50 minutes.
Therefore, 2t/3 = 50
or t = 75 minutes.

If she travels at S km/min, she will reach her destination in 75 minutes.

So, if she travels at 2S km/min, she will take half that time = 75/2 minutes = 37.5 minutes.