Speed of a motorboat in still water is 45, km | vedclass

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Question

(C) Let the speed of the stream be $x\, km/h$.The speed of the motorboat in still water is $45\, km/h$.Speed along the stream (downstream) $= (45 + x)

Vedclass · Accepted Answer

$2\, h\, 40\, min$

Vedclass · Answer

(C) Let the speed of the stream be $x\, km/h$.The speed of the motorboat in still water is $45\, km/h$.Speed along the stream (downstream) $= (45 + x)\, km/h$.Time taken to travel $80\, km$ downstream $= 1\, h\, 20\, min = 1 + \frac{20}{60} = 1 + \frac{1}{3} = \frac{4}{3}\, h$.Using the formula $	ext{Speed} = \frac{	ext{Distance}}{	ext{Time}}$:$45 + x = \frac{80}{4/3} = 80 	imes \frac{3}{4} = 60$.$x = 60 - 45 = 15\, km/h$.Speed against the stream (upstream) $= (45 - x) = 45 - 15 = 30\, km/h$.Time taken to cover $80\, km$ upstream $= \frac{	ext{Distance}}{	ext{Speed}} = \frac{80}{30} = \frac{8}{3}\, h$.Converting $\frac{8}{3}\, h$ into hours and minutes: $\frac{8}{3}\, h = 2\, h + \frac{2}{3} 	imes 60\, min = 2\, h\, 40\, min$.

Speed of a motorboat in still water is $45\, km/h$. If the motorboat travels $80\, km$ along the stream in $1\, h\, 20\, min$,then the time taken by it to cover the same distance against the stream will be:

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