A train running at 48 km/h crosses a man going with the speed of 12 km/h, in the same direction, in 18 seconds and passes a woman coming from the opposite direction in 12 seconds. The speed (in km/h) of the woman is :
Answer & explanation
Correct answer: option 1
Relative speed = 48 - 12 = 36 km/h
(When both moves in same direction )
36 km/h = 36 × \(\frac{5}{18}\) = 10 m/sec
Distance = Speed × Time
= 10 × 18 = 180 m
Now ,
In 2 nd case
Let speed of woman = x km/h
Relative speed = (x + 48) km/h
Time taken to cross each other = 12 sec
Relative Speed = \(\frac{180}{12}\) = 15 m/sec
15 m /sec = 15 × \(\frac{18}{5}\) = 54 km/h
Now , x + 48 = 54 km/h
x = 6 km/h
So speed of women = 6 km/h