1.

A train of length 120m crosses two cyclist A and B moving at speed of 9kmph and 12kmph respectively in same direction. Train crosses cyclist A in 16 seconds. Find the time in which train crosses cyclist B.1. 2 min2. 18 seconds3. 1 min4. 10 seconds5. 30 seconds

Answer» Correct Answer - Option 2 : 18 seconds

Given:

⇒ Speed of cyclist A = 9kmph = 9 × 5/18 = 5/2 m/s

⇒ Speed of cyclist B = 12kmph = 12 × 5/18 = 10/3 m/s

Let speed of train be a m/s.

Calculation:

Relative speed of train and cyclist A = a - 5/2

⇒ 120/(a - 5/2) = 16

⇒ 7.5 = a - 2.5

⇒ a = 10 m/s

Relative speed of train and cyclist B = 10 - 10/3 = 20/3 m/s

∴ Time in which train crosses cyclist B = 120/(20/3) = 18 seconds



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