The ratio of speed of a motor boat in still water and that of the current of water is $25 : 4 $. The motor boat goes distance downstream in 5 hours 15 minutes. How much time will it take to come back
Answer & explanation
Correct answer: option 4
The correct answer is option (4) :$t=7\frac{1}{4}hr $
Given,
Speed of motor boat in still water :Speed of current= 25 : 4
Let the speed of motor boat in still water be 25 km/h and that of speed of current be 4x km/hr.
Let the time taken by the motor boat to come back be t hrs.
then $29x×5\frac{1}{4}=21x×t$
$t= \frac{29}{4}hr$
$t=7\frac{1}{4}hr $