Two trains running in opposite directions cross a man standing on the platform in 32 seconds and 40 seconds respectively and they cross each other in 35 seconds. The ratio of their speeds is :
5 : 3
3 : 5
2 : 7
4 : 9
let the speeds of the two trains be x m/sec and y m/sec respectively. Then, length of the first train = 32x metres, and length of the second train = 40y metres.
.'. (32x + 40y)/(x + y) = 35 <=> 32x + 40y = 35x + 35y => 5y = 3x => x/y = 5/3 => x : y = 5 : 3
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