A swimmer swims from a point P against the current for 6 min and then swims back along the current for the next 6 min and reaches point Q. If the distance between Pand Q is 120 m then the speed of the current (in km/h) is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 0.6 km/h.
Let speed of swimmer in still water = u m/min
Let speed of current = v m/min
Upstream distance in 6 min = 6(u − v)
Downstream distance in next 6 min = 6(u + v)
Distance PQ = Downstream − Upstream
= 6(u + v) − 6(u − v)
= 6u + 6v − 6u + 6v
= 12v
Given PQ = 120 m
12v = 120
v = 10 m/min = 600/1000 km/h = 0.6 km/h