Question

a swimmer swims distance d upstream in 4 second and swims equal distance downstream in 2 second. the ratio of swimmer's speed in still water to the speed of river water will be?​

Answer 1

Answer:

answer in attachment

Answer 2

Concept:

Time for upstream, t = d/(v-u)

Time for downstream, t = d/(v+u)

where, d is the distance traveled, v and u are swimmer's speed in still water, and the speed of river water respectively.

Given:

The time required for upstream is 4 seconds and for downstream is 2 seconds.

Find:

The ratio of the swimmer's speed in still water to the speed of river water.

Solution:

Substituting the given values,

4 = d/(v-u)

4(v-u) = d

and, 2 = d/(v+u)

2(v+u) = d

Equating both the equations,

4(v-u) = 2(v+u)

4v - 4u = 2v + 2u

2v = 6u

v/u = 3/1

v : u = 3 : 1

Hence, the ratio of the swimmer's speed in still water to the speed of river water is 3:1.

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