The question is again rewritten here:

Question : A train left New Delhi for Chennai at 10 AM with a speed of 70 km/hr . Another Train also left New Delhi for Chennai at 11 AM with a speed of 90 km / hr . At what time 2nd Train will overtake the first train .Solution: The main point of understanding this sum is that the distance where the 2nd train will overtake the first one will be same . Also the time taken by the first trains will be 1 hr more than the 2nd trains.

Also remember that the slower train will take more time than the faster train.

Therefor we can create in one line .

90t = 70 (t+1) <br />

where t = time taken by the 2nd trains .

* See solution in the image also.

the distances are equal .

90t-70t=20t

:. t=70/20

:. t=3.5 Hrs

Therefor 2nd trains will overtake first one at (11 + 3.5) Hrs .

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