Question

a streamer goes downstream and covers the distance between two ports in 4 hours why it covers the same distance upstream in 5 hours if the speed of the stream is 2 kilometre per hour find the speed of the steamer in still water​

Answer 1

Given

• Downstream = 4 hours
• Upstream = 5 hours
• speed of the stream = 2 km/h

To Find

• speed of the steamer in still water.

SOLUTION

Let the speed of the streamer be x.

$\large\tt \: downstream = (x + 2)$

$\large\tt \: upstream = (x - 2)$

4 hours in Downstream = 4(x+2)

5 hours in Upstream = 5(x-2)

According to question

$\large\tt \: ⇒4(x + 2) = 5(x - 2)$

$\large\tt \: ⇒4x + 8 = 5x - 10$

$\large\tt \: ⇒4x - 5x = - 10 - 8$

$\large\tt \: ⇒- 1x = - 18$

$\large\tt ⇒ x = {\frac{ - 18}{ - 1}}$

$\boxed{\large\tt\ \: x = 18}$

Hence, speed of the steamer in still water is 18 km/hr.

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Extra information

rules of add and subtract

• Plus and plus becomes plus
• minus and minus becomes plus
• minus and plus becomes minus
• plus and minus becomes minus

Note :- For upstream there's always Minus. For downstream there's always plus.