2 trains started simultaneously at 11am from a to b , moving towards b to a respectively, and crossed each other at 3pm . if the train starting from a reached its destination 88 minutes before the other train, when did the train starting from b to a reach ?

Hi,

We know that 

v = sqr root(ab), where v = time in which they meet and a and b are time after meeting when they reach their destination. 

Here v= 4 hours i.e. 240 minutes.

Let's assume x be the time that first car takes to reach its destination after meeting.

So, second car must take x+88 minues.

Now, 240 = sqrroot [x(x+88)]

Solving this we can get the value of x.

From this we can estimate the travel time of both the trains.