SOLUTION: Time taken by two trains running in opposite directions to cross a man stading on the platform in 28 seconds and 18 seconds respectively. It took 26 seconds for the trains to cross

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Question 1189697: Time taken by two trains running in opposite directions to cross a man stading on the platform in 28 seconds and 18 seconds respectively. It took 26 seconds for the trains to cross each other. What is the ratio of their speeds?
a)2:3 b)3:2 c)1:4 d)4:1

Answer by ikleyn(52855) About Me  (Show Source):
You can put this solution on YOUR website!
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Time taken by two trains running in opposite directions to cross a man stading on the platform
in 28 seconds and 18 seconds respectively. It took 26 seconds for the trains to cross each other.
What is the ratio of their speeds?
a)2:3 b)3:2 c)1:4 d)4:1
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Train 1 length = x meters;  train 2 length = y meters;  

Train 2 speed  = u m/s;     train 2 speed  = v m/s.


We are given that

    x%2Fu = 28  (seconds);   

    y%2Fv = 18  (seconds).


Also, we are given  

    %28x+%2B+y%29%2F%28u+%2B+v%29 = 26  seconds.


It implies  x = 28u;  y = 18v;  %2828u+%2B+18v%29%2F%28u+%2B+v%29 = 26.

From the last equation

    28u + 18v = 26u + 26v,

    28u - 26u = 26v - 18v,

       2u     =    8v

        u%2Fv = 8%2F2

        u%2Fv = 4.


ANSWER.  The ratio of their speeds is u/v = 4, 

         or  speed%5Btrain1%5D : speed%5Btrain2%5D = 4.

Solved.