Question

If a man takes two hours to row 7 km upstream or 15 km downstream, what is the speed of current

Answer 1

The speed of current is 2 km/hr

Step-by-step explanation:

Given: A man takes two hours to row 7 km upstream

$\Rightarrow v-u = \frac{7}{2}$

A man takes two hours to row 15 km downstream,

$\Rightarrow v+u = \frac{15}{2}$

By subtracting both equation we get,

$\Rightarrow 2u = \frac{15}{2} - \frac{7}{2}$

$\Rightarrow 2u = \frac{8}{2}$

$\Rightarrow u = 2 km/hr$

The speed of current is 2 km/hr