Question

The speed of boat in still water is $10$ km per hr. If the boat goes $37.5$ km upstream in $5$ hours, find the speed of the stream.

• A. $2.5$ km/hr
• B. $1.5$ km/hr
• C. $3.4$ km/hr
• D. $5.4$ km/hr

Answer 1

The correct option is A $2.5$ km/hr

Solution:
Given Equation: Speed of boat in still water $=10$ km\hr
Boat Travels a distance of $37.5$ km in time $5$ hr.
Factor to consider speed of stream be 's'
According to the formula:
Speed $=\frac{Distance}{Time}$
Total speed = speed of boat in still water and speed of stream

Since the boat travels upstream
Total speed = Speed of boat in still water - speed of water in stream
$10-s=\frac{37.5}{5}$

$10-s=7\frac{1}{2}$
$s=2.5$ km\hr