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 $105$ km downstream and return.

• A. $11$ hours
• B. $12$ hours
• C. $13$ hours
• D. $14$ hours

Answer 1

The correct option is A $11$ hours

Speed of a boat in still water $=22$km/hr

Speed of water stream $=8$km/hr

Speed of boat in downstream $=(22+8)=30$km/hr

(boat travels in the direction of water stream)

Speed of boat in return $=22-8=14$km/hr

(boat travels in opposite direction of water stream)

Time taken in traveling downstream $105$km $=\frac{105}{30}$hr

Time taken in traveling return $105$ km $=\frac{105}{14}$ hr

Total time $=\frac{105}{30}$ $+\frac{105}{14}=11$ hrs