Question 123

Train A, whose length is 328 metre can cross a 354 metre long platform in 11 seconds. Train B can cross the same platform in 12 seconds. If the speed of train— B is 7/8th of the speed of train—A, what is the length of train—B ? (in m)

Solution

Speed = $$\frac{\textrm{Length of train + Length of platform}}{Time}$$

=> Speed of train A = $$\frac{328 + 354}{11}$$

= $$\frac{682}{11} = 62$$ m/s

=> Speed of train B = $$\frac{7}{8} \times 62$$

= $$\frac{217}{4}$$ m/s

Let length of train B = $$l$$

=> $$\frac{l + 354}{12} = \frac{217}{4}$$

=> $$l + 354 = \frac{217}{4} \times 12$$

=> $$l + 354 = 217 \times 3 = 651$$

=> $$l = 651 - 354 = 297$$ metre

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