A boatman covers a distance of 24 km against water current and 36 km along the water current and takes 6 hours each time. Find the speed of water current.

Correct option is C

Given:

Distance against the current = 24 km

Distance along the current = 36 km
Time taken = 6 hours each
Formula Used:
Let the speed of boat and current be x km/hr and y km/hr.
Upstream speed = (x – y) km/hr
Downstream speed = (x + y) km/hr

Solution:

As we know,

Speed = distance/time

=> (x – y) = 24/6

=> x – y = 4      --- (1)

=> (x + y) = 36/6

=> x + y = 6      --- (2)

Subtract equation (1) from equation (2)

=> 2y = 2

=> y = 1

∴ Speed of current is 1 km/hr.