Question

A boat can travel with a speed of 18 mph in still water. The speed of the stream is 6 mph. Find the time taken by the boat to go 72 miles downstream.

• A. 3 h
• B. 5 h
• C. 6 h
• D. 4 h 30 min

Answer 1

The correct option is A 3 h

Speed of the boar in still water = 18 mph

Speed of the stream = 6 mph


We know,
Speed downstream = Speed of boat + Speed of stream
= 18 + 6
= 24 mph

So, the time taken by the boat is:
$\text{Time}=\frac{Distance}{Speed}$

$=\frac{72}{24}$

= 3 h

Hence, the time taken by the boat to go 72 miles downstream is 3 hours.