M4maths Previous Puzzles

24 Jun 2022 Time Distance & Speed

A train crosses a man running in opposite direction in 21 seconds and same train crosses a 240 meters long platform in 33 seconds. If speed of man is 15 km/hr, then speed of train is

OPtion

1) 100.50 km/hr
2) 96.25 km/hr
3) 94.25 km/hr
4) 89.50 km/hr
5) 86.75 km/hr
6) 93.50 km/hr
7) 90.75 km/hr
8) 98.25 km/hr
9) 99.75 km/hr
10) None of these

Solution

Given, speed of man=15 km/hr=15*(5/18)=25/6 m/s
Let speed of train = x m/s
Relative speed of train w.r.t. man = (x + 25/6) m/s
Length of train = Time taken to cross man * Relative speed = 21*(x + 25/6)
Also, given train crosses 240 m platform in 33 sec
Length of (train+Platform) = Time taken to cross platform * Speed of train
21*(x + 25/6) + 240 = 33*x
21x + 175/2 + 240 = 33x
x = 655/24 m/s = (655/24)*(18/5) = 98.25 km/hr
Correct Option 8)

Correct Option: 8 Best Solution (0)