Topic : BOATS & STREAMS PYQ's 

FORMULAE OF BOATS & STREAMS

Q1. A man takes half time in rowing a certain distance downstream than upstream. What is the ratio of the speed in still water to the speed of current? [CSAT 2020]

(a) 1:2

(b) 2:1

(c) 1:3

(d) 3:1

Answer: (d)

Solution:

Given that,

Time taken downstream = (1/2) time in upstream

Let,

Speed of boat = B km/hr

Speed of stream = S km/hr

Distance covered = D km

Now,

Downstream = (B + S) km/hr

Upstream = (B - S) km/hr

2D/(B + S) = D/(B - S) .....(GIVEN)

B = 3S

Thus B/S = 3/1

Therefore the required ratio = 3 : 1

Hence option (d) is correct