Boats and Streams - General Aptitude

Q1:

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

A 1 km/hr

B 1.5 km/hr

C 2 km/hr

D 2.5 km/hr

ANS:A - 1 km/hr

Suppose he move 4 km downstream in x hours. Then,

Speed downstream = 4 km/hr.
x
Speed upstream = 3 km/hr.
x
48 + 48 = 14 or x = 1 .
(4/x) (3/x) 2
So, Speed downstream = 8 km/hr, Speed upstream = 6 km/hr.
Rate of the stream = 1 (8 - 6) km/hr = 1 km/hr.
2