The distance between Y to Z is ‘m’ km. And the distance between X to Y is ‘m+56’ km

Q. The distance between Y to Z is ‘m’ km. And the distance between X to Y is ‘m+56’ km. Boat A travels downstream from point X to Y and Boat B travels upstream from Y to Z. The speed of boat A in still water is 20℅ of ‘m’ and its equal to the upstream speed of boat B. Boat A travels downstream and it takes 20 minutes more time than the Boat B travels in Upstream. What is the distance between Y and Z, if the speed of the current is the same in both cases that is 8 km/hr?

A. 150 km

B. 224 km

C. 200 km

D. 194 km

E. None of these

Sol:

The speed of boat A in still water = 20/100 of m

=> 0.2 m km/hr

Speed of the current = 8 km/hr

Downstream speed of boat A = (0.2m + 8) km/hr

Boat A in still water = upstream speed of boat B

=> 0.2m

So, upstream speed of boat B = 0.2m km/hr

m+56/0.2m+8 – m/0.2m = 1/3

m+56/0.2m+8 = 16/3

3m + 168 = 3.2m + 128

0.2m = 40

m = 200

So, Distance between Y and Z = 200 km