Math, asked by Shivam691, 1 year ago

A person rowing at the rate of 5km/h in still water, takes thrice as much time in going 40km upstream as in going 40km downstream. Find the speed of stream.


wvaibhava: yes it is right

Answers

Answered by siddhartharao77
51
Let the speed of the stream = x km/hr.

Then the speed of the boat in downstream = (5 + x)km/hr.

Then the speed of the boat in upstream = (5 - x)km/hr.

Given that Distance = 40km.

Then the time is taken in downstream = 40/(5 + x)

Then the time is taken in upstream = 40/(5 - x).

Given that the Upstream time = 3 * Downstream Time

40/(5 - x) = 3 * 40/(5 + x)

5 + x = 3(5 - x)

5 + x = 15 - 3x

5 + x - 15 = -3x

-10 + x = -3x

x = -3x + 10

4x = 10

x = 10/4

x = 2.5.


Therefore the speed of the stream = 2.5km/hr.


Hope this helps!

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Answered by ChetanaK
19
Let speed of the stream be = x km/hr

Speed of the Boat downstream = (5+x) km/hr
Speed of the Boat upstream= (5-x) km/hr

Given that Distance = 40km

Time = Distance/Speed

Time taken (Downstream) =
40 \div 5 + x
Time taken (Upstream) =
40 \div 5 - x

Given that Upstream time = 3 × Downstream

40/5 - x = 3 × 40/5 + x

(40/40 gets cancelled)

5 + x = 3 ( 5 - x )
5 + x = 15 - 3x
3x + x = 15 - 5
4x = 10
Therefore, x = 10/4 = 2.5 km/hr

Therefore, SPEED of the stream = 2.5 kmph.

Hope this helps!
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