Question

26. A motor boat whose speed is 15 km/hr in still water goes 30 km down stream and comes back in a total of 4 hours 30 minutes. determine the speed of the stream​

Answer 1

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 - x) km/hr.

30 + 30 = 4 1

(15 + x) (15 - x) 2

900 = 9

225 - x2 2

9x2 = 225

x2 = 25

x = 5 km/hr.

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PLZ MARK AS BRAINLY❤

Answer 2

Answer:

Let the speed of the stream be x km/hr. Then,

Speed downstream = (15 + x) km/hr,

Speed upstream = (15 - x) km/hr

So we know from question that it took 4(1/2)hrs to travel back to same point.

So,

\begin{aligned}

\frac{30}{15+x} - \frac{30}{15-x} = 4\frac{1}{2} \\

=> \frac{900}{225 - x^2} = \frac{9}{2} \\

=> 9x^2 = 225 \\

=> x = 5 km/hr