Question

The speed of a boat in still water is 8 km/h, while it takes 2 hours for the boat to cover a distance of 20 km downstream. What is the speed (in km/h) of the stream?

• A. 2.5
• B. 1.75
• C. 2
• D. 1.5

Answer 1

Answer:

C. 2

Downstream speed = Distance ÷ Time = $( \frac{20}{2} = 10 ) km/h$

We know:
Downstream speed = Speed of boat in still water + Speed of stream

So,
$( 10 = 8 + \text{stream speed} )$

Stream speed = ( 10 - 8 = 2 ) km/h

Answer: 2 km/h