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The speed of a boat along the stream is 12 km/hr and against the stream is 8 km/hr. The time taken by the boat to sail 24 km in still water is?

12 hrs
23 hrs
32.4 hrs
41.2 hrs

Answer:- 1

Explanation:-

Solution:

\begin{aligned} Speed of downstream , \\ D  = 12 k m / h \\ Speed of upstream , \\ U  = 8 k m / h \\ Speed of boat in still water \\ = \frac{D + U}{2} \\ = \frac{20}{2} = 10 k m / h \\ Time taken by the boat in still water \\ = \frac{24 k m}{10 k m / h r} \\ = 2.4 h o u r s \end{aligned}

$\eqalign{ & {\text{Speed of downstream , }} \cr & {\text{D = }}12km/h \cr & {\text{Speed of upstream , }} \cr & {\text{U = }}8km/h \cr & {\text{Speed of boat in still water }} \cr & {\text{ = }}\frac{{{\text{D}} + {\text{U}}}}{2} \cr & = \frac{{20}}{2} = 10km/h \cr & {\text{Time taken by the boat in still water}} \cr & {\text{ = }}\frac{{24km}}{{10km/hr}} \cr & = 2.4hours \cr}$

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", "dateCreated": "7/24/2019 10:09:12 AM", "author": { "@type": "Person", "name": "Nitin Sir" } }, "suggestedAnswer": { "@type": "Answer", "text": "

Solution:

\begin{aligned} Speed of downstream , \\ D  = 12 k m / h \\ Speed of upstream , \\ U  = 8 k m / h \\ Speed of boat in still water \\ = \frac{D + U}{2} \\ = \frac{20}{2} = 10 k m / h \\ Time taken by the boat in still water \\ = \frac{24 k m}{10 k m / h r} \\ = 2.4 h o u r s \end{aligned}

$\eqalign{ & {\text{Speed of downstream , }} \cr & {\text{D = }}12km/h \cr & {\text{Speed of upstream , }} \cr & {\text{U = }}8km/h \cr & {\text{Speed of boat in still water }} \cr & {\text{ = }}\frac{{{\text{D}} + {\text{U}}}}{2} \cr & = \frac{{20}}{2} = 10km/h \cr & {\text{Time taken by the boat in still water}} \cr & {\text{ = }}\frac{{24km}}{{10km/hr}} \cr & = 2.4hours \cr}$ ", "dateCreated": "7/24/2019 10:09:12 AM" } }

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