Question

Train A, travelling at 84 kmph, overtook
train B, traveling in the same direction, in 10 seconds. f train B had been traveling at twice its speed, then train A would have taken 22.5 seconds to overtake it. Find the length of train B, given that it is half the length of train A.
A. 180 m
C. 200 m
E. 50 m
B. 100 m
D. 150 m

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Answer 1

Hello Dear,

◆ Answer -

Length of train B = 50 m

◆ Explaination -

For overtaking train B, train A has to travel distance equal to length of train A + length of train B. Let this total distance be l. Let v be speed of train B.

Initially,

l = (84-v) × 10/3600 ...(1)

Later,

l = (84-2v) × 22.5/3600 ...(2)

Equating (1) & (2),

(84-v) × 10/3600 = (84-2v) × 22.5/3600

840 - 10v = 1890 - 45v

45v - 10v = 1890 - 840

35v = 1050

v = 1050 / 35

v = 30 km/h

Now l will be,

l = (84-v) × 10/3600

l = (84-30) × 10/3600

l = 54/360

l = 0.15 km

l = 150 m

Length of train B is -

Train B = l × B / (A+B)

Train B = 150 × 1/(1+2)

Train B = 50 m

Therefore, length of train B is 50 m.

Thanks dear...