A motorboat whose speed is $9$ km/hr in still water, goes $15$ km downstream and comes back in a total time of $3$ hours $45$ minutes. Find the speed of the stream.

3 k m / h r

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9 k m / h r

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6 k m / h r

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2 k m / h r

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Solution

The correct option is A $3 k m / h r$
$L e t s p e e d o f s t r e a m = x k m / h r t h e n (\frac{15}{9 + x}) + (\frac{15}{9 - x}) = 3 + (\frac{3}{4}) h o u r 15 (\frac{9 - x + 9 + x}{81 - x^{2}}) = (\frac{15}{4}) 72 = 81 - x^{2} ∴ x^{2} = 81 - 72 ∴ x = 3 k m / h r$

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Similar questions

Q. A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is:

Q12. A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. The speed of the stream (in km/hr) is-

Q. A motor boat whose speed is

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in still water goes

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km downstream and comes back in a total of

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Q. A motorboat that has a speed of 9 km/hr in still water, goes 15 km downstream and comes back in 3 hours 45 minutes. The speed of the stream is .

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15

km/hr. It goes

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km upstream and return downstream to the original point in

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hrs

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A motorboat whose speed is 9km/hr in still water, goes 15 km downstream and comes back in a total time of 3 hours 45 minutes. Find the speed of the stream.

The correct option is A 3km/hrLetspeedofstream=xkm/hrthen(159+x)+(159−x)=3+(34)hour15(9−x+9+x81−x2)=(154)72=81−x2∴x2=81−72∴x=3km/hr

A motorboat whose speed is $9$ km/hr in still water, goes $15$ km downstream and comes back in a total time of $3$ hours $45$ minutes. Find the speed of the stream.

The correct option is A $3 k m / h r$
$L e t s p e e d o f s t r e a m = x k m / h r t h e n (\frac{15}{9 + x}) + (\frac{15}{9 - x}) = 3 + (\frac{3}{4}) h o u r 15 (\frac{9 - x + 9 + x}{81 - x^{2}}) = (\frac{15}{4}) 72 = 81 - x^{2} ∴ x^{2} = 81 - 72 ∴ x = 3 k m / h r$