A boat moves down stream at the rate of 1 km in 6 minutes and
upstream at the rate of 1 km in 10 minutes. The speed of current is
Select
A) 2 kmph
B) 3 kmph
C) 4 kmph
D) 5 kmph
E) 6 kmph

Rationale: if speed ( in kmph ) of the boat = b and current = c , then in downstream time taken ( in hrs . ) = 1 / ( b + c ) = 6 / 60 = 1 / 10 or b + c = 10 - - - ( i ) & in upstream time taken ( in hrs . ) = 1 / ( b - c ) = 10 / 60 = 1 / 6 or b - c = 6 - - - ( ii ) from ( i ) & ( ii ) , b = 8 , c = 2 answer : a
Answer: A