Ishwar is rowing a boat. He takes half time in moving a certain distance downstream than upstream . What is the ratio of the rate of boat in still water to the rate of current ?
Solution
Correct Answer: Option D
Let, Speed of the boat u and speed of current v
We have to find out u : v ?
If x distance is covered then time for downstream is = {x/(u+v)}
and time for upstream is = {x/(u-v)}
According the question, {x/(u+v)} = [(1/2){x/(u-v)}]
=> {(u+v)/(u-v)} = 2 => u + v = 2u - 2v
=> u - 2u = -2v - v => -u = -3v =>u/v = 3/1
∴ u : v = 3 : 1
We have to find out u : v ?
If x distance is covered then time for downstream is = {x/(u+v)}
and time for upstream is = {x/(u-v)}
According the question, {x/(u+v)} = [(1/2){x/(u-v)}]
=> {(u+v)/(u-v)} = 2 => u + v = 2u - 2v
=> u - 2u = -2v - v => -u = -3v =>u/v = 3/1
∴ u : v = 3 : 1
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