The ratio of the speeds of a motor boat and that of the current of water is 26 : 4. The boat goes certain distance against the current in 6 hrs. The time taken by the boat to come back is ______
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 4 hrs 24 minutes
Let the speed of the boat in still water be 26k and the speed of the current 4k. Then the upstream and downstream speeds are
\(\text{Upstream} = 26k - 4k = 22k\)
\(\text{Downstream} = 26k + 4k = 30k\)
Going against the current takes 6 hrs, so the distance is
\(22k \times 6 = 132k\)
Coming back with the current:
\( \displaystyle \text{Time} = \frac{132k}{30k} = 4.4 \text{ hrs} \)
\(0.4 \text{ hr} = 0.4 \times 60 = 24 \text{ minutes}\)
So the boat comes back in 4 hrs 24 minutes.