NCHMCT JEE 2014 Question Paper with solutions for online practice

Question : 23 of 200

Marks: +1, -0

A man rows downstream 30 km and upstream 18 km, taking 5 hours each time. What is the velocity of the stream (current)?

1.2 km/hr
1.5 km/hr
2.5 km/hr
1.8 km/hr

Solution:

Let man’s velocity in the river is u km/hr and current velocity is v km/hr.
Downstream velocity = (u + v) km/hr
upstream velocity = (u – v) km/hr.
From question,
u + v =

{30}/5

u + v = 6 ... (i)
and u - v =

{18}/5

= 3.6 ... (ii)
From (i) and (ii), we have
velocity of stream (v) = 1.2 km/hr.

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