Question 35

Train A, 220m long, can cross a platform 340 m long in 32 sec. If the respective ratio of speed of trains A and B is 7 : 9 and the length of train B is 270 m, how much time (in sec) would train B take to cross an electric pole ?

Solution

Length of train A = 220 m

=> Speed of train A = $$\frac{220 + 340}{32}$$

= $$\frac{560}{32} = 17.5$$ m/s

Speed of train A : Speed of train B = 7 : 9

=> Speed of train B = $$\frac{9}{7} \times 17.5$$

= $$9 \times 2.5 = 22.5$$ m/s

Length of train B = 270 m

$$\therefore$$ Time taken by train B to cross the pole = $$\frac{270}{22.5}$$

= 12 sec

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