Question
A boat leaves it's dock and travels upstream at a speed of 40 km/hr and then returns to the dock. What is the speed of the stream if they average speed of the entire trip is 60 km/hr?
Answer: Option D
:
D
Speed of stream = x.
Speed of boat = b.
Given, b - x = 40.
Also,
2[(b+x)(b−x)](b+x+b−x)=60⇒2(b+x)(40)2b=60.
Solving we get b= 2x.
2x - x = 40 , x = 40 (d).
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:
D
Speed of stream = x.
Speed of boat = b.
Given, b - x = 40.
Also,
2[(b+x)(b−x)](b+x+b−x)=60⇒2(b+x)(40)2b=60.
Solving we get b= 2x.
2x - x = 40 , x = 40 (d).
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