A train travels the distance between stations P and Q at a speed of 126 km/h, while in the opposite direction it comes back at 90 km/h. Another train travels the same distance at the average speed of the first train. The time taken by the second train to travel 525 km is:

A. 5 hours

B. 4 hours

C. 5 hours 20 minute

D. 4 hours 20 minute

Answer: Option A

Solution(By Examveda Team)

$$\eqalign{ & {\text{Average speed}} = \frac{{2 \times 90 \times 126}}{{216}} \cr & = \frac{{2 \times 5 \times 126}}{{12}} \cr & = 105{\text{ km/h}} \cr & {\text{Time}} = \frac{{525}}{{105}} = 5{\text{ hours}} \cr} $$