Here is a relatively easy quantitative reasoning question from this topic
1. 50 minutes
2. 75 minutes
3. 150 minutes
4. 100 minutes
5. 37.5 minutes
Correct Answer : Choice 5. 37.5 minutes
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.