Multiple choice

Train A crosses a tower with a speed of 86.4 km/h in ‘t’ seconds while another train B crosses a platform of 80 m length in ‘2t’ seconds with a speed of 108 km/h. If train B is 100% more in length than that of train A then find the length of train B?

  1. 300 m

  2. 400 m

  3. 360 m

  4. 280 m

  5. 320 m
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Train A: speed = 86.4 km/h = 24 m/s. Length = LA, crosses tower in t seconds, so LA = 24t. Train B: speed = 108 km/h = 30 m/s, length LB = 2LA (100% more), crosses 80m platform in 2t seconds. So LB + 80 = 30 × 2t = 60t. Substituting LB = 2LA = 2 × 24t = 48t: 48t + 80 = 60t, giving 12t = 80, so t = 20/3. Then LB = 48 × (20/3) = 320m. Option E is correct.

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