# CAT Practice : Speed Time, Races

## Trains A and B

Q.26: Two trains A and B are 100 m and 150 m long and are moving at one another at 54 Km/hr and 36 Km/hr respectively. Arun is sitting on coach B1 of train A. Calculate the time taken by Arun to completely cross Train B.
1. 10 s
2. 6 s
3. 4 s
4. 8 s

Choice B.6 s

## Detailed Solution

Speed of A = $54 * \frac{1000}{60*60}$ = 15 m/s

Speed of B = $36 * \frac{1000}{60*60}$ = 10 m/s

Relative speed = S1 + S2 = 15 + 10 m/s = 25 m/s

The length that needs to be crossed = length of train B = 150 m. Therefore time taken = $\frac{150}{25}$ = 6s.

What is the time taken for trains to completely cross each other? The length that needs to be crossed = 100 + 150 = 250 m. Time taken = $\frac{250}{25}$ = 10 s.

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## More questions from Speed Time, Races

"Life is a race ... if you don't run fast ... you will be like a broken undaa" - Veerusahasra Buddhi