Boats and Streams - Quantitative Aptitude (MCQ) questions for Q. 47
Q. A boat with speed 15 km/hr in standing water goes 30 km downstream and returns in a total of 4.5 hours. What is the speed of current?- Published on 12 Jun 15a. 4 kmph
b. 6 kmph
c. 5 kmph
d. 8 kmph
ANSWER: 5 kmph
Speed of the boat in still water: 15 km/hr
Speed of boat downstream: (15+x)km/hr where x is speed of the current.
The boat travels 30 km downstream and then 30 km upstream and takes 9/2 hours.
Total time= Time taken to travel downstream + Time taken to travel upstream
=> 4/5= (30/(15+x))+(30/(15-x))
=>x= 5
