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# Two trains running in opposite directions cross a man standing on the platform in 27 and 17 seconds respectively and they cross each other in 23 seconds. What is the ratio of their speeds?

[ A ]    Insufficient data
[ B ]    3 : 1
[ C ]    1 : 3
[ D ]    3 : 2
 Answer : Option D Explanation : Let the speed of the trains be x and y respectively length of train 1 = 27x length of train 2 = 17y Relative speed = x+ y Time taken to cross each other = 23 sec $27x + 17 y \over x + y$ = 23 $27x + 17 y$ = 12 (x + y) 4x = 6y $x \over y$ = $6 \over 4$ = $3 \over 2$ = 3 : 2