A boat covers a certain distance downstream in 1 hour, while it comes back in 1.30 hours.
A boat covers a certain distance downstream in 1 hour, while it comes back in 1.30 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?
Answer/Solution
15
Steps/Work
Let the speed of the water in still water =x
Given that speed of the stream = 3 kmph
Speed downstream =(x+3) kmph
Speed upstream =(x−3) kmph
He travels a certain distance downstream in 1 hour and come back in 1 1⁄2 hour.
i.e., distance travelled downstream in 1 hour = distance travelled upstream in 1 1⁄2 hour
Since distance = speed × time, we have
(x+3)×1=(x−3)3/2
⇒2(x+3)=3(x−3)
⇒2x+6=3x−9
⇒x=6+9=15 kmph
Answer is E.
Given that speed of the stream = 3 kmph
Speed downstream =(x+3) kmph
Speed upstream =(x−3) kmph
He travels a certain distance downstream in 1 hour and come back in 1 1⁄2 hour.
i.e., distance travelled downstream in 1 hour = distance travelled upstream in 1 1⁄2 hour
Since distance = speed × time, we have
(x+3)×1=(x−3)3/2
⇒2(x+3)=3(x−3)
⇒2x+6=3x−9
⇒x=6+9=15 kmph
Answer is E.