Question

A man rows to a place 48 km distance and come back in 14 h. He finds that he can row 4 km with the stream at the same time as 3 km against the stream. The rate of the stream is

विकल्प

• 1 km/h

• 1.5 km/h

• 2 km/h

• 2.5 km/h

Answer 1

1 km/h
Explanation:
Suppose, man move 4 km downstream in x hours.
Then, Speed downstream = `(4/x)`km/h.

Speed upstream = `(3/x)`km/h.

∴ `48/((4/x))+48/((3/x))=14⇒x=1/2`

So, speed downstream = 8 km/h,
speed upstream = 6 km/h.

Rate of the stream = `1/2(8-6)`km/h = 1 km/h.