Question

The speed of a boat in still water is $8$ km/hr and speed of the stream is $3$ km/hr. Find time taken by boat to go $30$ km upstream.

• A. $2$ hrs
• B. $7$ hrs
• C. $3$ hrs
• D. $6$ hrs

Answer 1

The correct option is D $6$ hrs

speed of the boat=$8km/hr$

speed of the stream=$3km/hr$

If the speed of the boat in still water is $xkm/hr$ and speed of the stream is $ykm/hr$ then $speedupstream=(x-y)km/hr$

Therefore $speedupstream=8-3=5km/hr$

$distance=30km$

$time=\frac{distance}{speed}$

$\Rightarrow time=\frac{30}{5}$

$\Rightarrow time=6hrs$