Question

Two boats A and B start towards each other from two places, 108 km apart. Speed of the boats A and B in still water are 12 km/h and 15 km/h respectively. If A proceeds down and B up the stream, they will meet after:
A.4.5 hours
B.4 hours
C.5.4 hours
D.6 hours

Answer 1

Two boats A and B meet after=4h

Answer 2

Answer:

Step-by-step explanation:

Let the speed of stream = y km/h  

Since Boat A is moving downstream with 12 km/h  

Speed of boat A  

= (12+y)(12+y)km/h  

Since Boat is moving upstream with 15km/h

Speed of boat B  

= (15−y)(15−y) km/h  

Both the boats are moving in opposite direction

Relative speed of A and B  

=12+y+15−y12+y+15−y

=27 km/h

Time=DistanceRelative Speed=10827=4DistanceRelative Speed=10827=4 hours