The speed of a boat in still water is 10 km/h. If its speed downstream is 18 km/h, the distance travelled by the boat upstream in 5 hours is :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 10 km
Let the speed of the stream be s km/h. Downstream the stream adds to the boat's speed:
\(10 + s = 18\)
\(s = 8\)
Upstream the stream subtracts:
\(10 - 8 = 2\) km/h
Distance upstream in 5 hours:
\(2 \times 5 = 10\) km