Question

A boat can travel with a speed of $22$ km/hr in still water. If the speed of the stream is $8$ km per hr, find time taken by it to go $135$ km downstream.

• A. $9\frac{1}{2}$ hours
• B. $5\frac{7}{2}$ hours
• C. $8\frac{4}{5}$ hours
• D. $4\frac{1}{2}$ hours

Answer 1

Answer: (D)

$4\frac{1}{2}$ hours

Given: Boat travels at a speed of $22$ km/hr.

Speed of stream is $8$ km/hr.

Speed of boat to go downstream $=22+8=30$ km/hr

Distance to go downstream $=135$ km

Hence, to calculate time taken:

Speed $=\frac{Distance}{time}$

Time $=\frac{135}{30}$ $=4\frac{1}{2}$ hours