Question

A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?
A.4 km/hr
B.6 km/hr
C.8 km/hr
D.Data inadequate

Answer 1

Let,

Vb = velocity of the boat in still water

Vr = velocity of the river


So, net velocity while moving downstream

= Vb + Vr

Given, Vb + Vr = 16 km/2 hr = 8 km/hr ———————(1)

Net velocity while moving upstream

= Vb - Vr

Given, Vb - Vr = 16 km/4 hr = 4 km/hr ———————(2)

Adding, (1) and (2),

We get, 2 * Vb = 12 km/hr

or, Vb = 6 km/h
So, velocity of boat in still water is 6 km/hr.
your answer is b