Question

Solve this question


25 points​

Answer 1

Answer: Let the speed of the stream be = u km/ph

Let the speed of the boat be = v km/ph

speed upstream will be = v – u km/ph

speed downstream will be = v + u km/ph

30 km upstream in time duration = 30 / (v – u) hr

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

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

Similarly,

40 /(v – u) + 55 / (v +u) = 13 hr 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 km/ph and

u = 3 km/ph

Step-by-step explanation:

Answer 2

Answer:

Let the speed of the stream be =u km/ph

Let the speed of the boat be = v km/ph

speed upstream will be = v − u km/ph

speed downstream will be = y + u km/ph

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

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

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

40/(v - u) + 55 / (v +u) = 13 hr 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 km/ph and

u=3 km/min