A man can row against the current frac{3}{4} | vedclass

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(D) Let the speed of the man in still water be $u$ and the speed of the current be $v$.Speed against the current $(u - v) = \frac{	ext{Distance}}{	e

Vedclass · Accepted Answer

$5:1$

Vedclass · Answer

(D) Let the speed of the man in still water be $u$ and the speed of the current be $v$.Speed against the current $(u - v) = \frac{	ext{Distance}}{	ext{Time}} = \frac{3/4 	ext{ km}}{15/60 	ext{ h}} = \frac{3}{4} 	imes 4 = 3 	ext{ km/h}$.Speed with the current $(u + v) = \frac{	ext{Distance}}{	ext{Time}} = \frac{3/4 	ext{ km}}{10/60 	ext{ h}} = \frac{3}{4} 	imes 6 = 4.5 	ext{ km/h}$.Adding the two equations: $(u - v) + (u + v) = 3 + 4.5 \implies 2u = 7.5 \implies u = 3.75 	ext{ km/h}$.Subtracting the first from the second: $(u + v) - (u - v) = 4.5 - 3 \implies 2v = 1.5 \implies v = 0.75 	ext{ km/h}$.The ratio of his speed to that of the current is $u : v = 3.75 : 0.75 = 5 : 1$.

$A$ man can row against the current $\frac{3}{4}$ of a kilometre in $15$ minutes and returns the same distance in $10$ minutes. The ratio of his speed to that of the current is

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