Question

A boat goes 30 km upstream and 44 km downstream in 10 hours. In 13 hours,it can go 40km upstream and 55km downstream . Determine the speed of the stream and that of the boat in still water.





as soon as pls give the answer​

Answer 1

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