Question

19. A boat can go 75 km downstream in 5 hours and 44 km upstream in 4 hours. Find
speed of the boat in still water (ii) the rate of the current.​

Answer 1

Answer:

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Step-by-step explanation:

Let the speed of the stream be = u kmph

let the speed of the boat be = v kmph

speed upstream will be = v - u kmph

speed downstream will be = v + u kmph

30 km upstream in time duration = 30 / (v - u) hrs

44 km down stream in time duration = 44 / (v + u) hrs

44 / (v + u) + 30 / (v -u) = 10 hrs --- (1)

Similarly,

40 /(v - u) + 55 / (v +u) = 13 hrs Multiply with 3/4:

30/(v-u) + 165 / 4(v+u) = 39/4 --- (2)

Now (1) - (2) => [44 - 165/4] / (v+u) = 10 - 39/4 = 1/4

=> v + u = 11 --- (3)

Substitute this in (1) to get:

44/11 + 30/(v-u) = 10

=> v - u = 30/6 = 5 --- (4)

Solving (3) and (4) , we get : v = 8 kmph and u = 3 kmph

Answer 2

Answer: 24km

Step-by-step explanation: