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 **
Speed of motor boat : speed of current = $26:4$
Let boat speed in still water = $26k$
Let current speed = $4k$
Upstream speed = $26k - 4k = 22k$
Downstream speed = $26k + 4k = 30k$
Let the distance be $d$.
Upstream time is given: $6$ hours
$\displaystyle \frac{d}{22k} = 6 \quad\Rightarrow\quad d = 132k$
Downstream time:
$\displaystyle \text{Time} = \frac{d}{30k} = \frac{132k}{30k} = \frac{132}{30} = 4.4$
Time taken to come back = 4.4 hours= 4 hrs 24 minutes