Question

A boat takes 4 hours to go 44 km downstream and it can go 20 km upstream in the same time. Find the speed of the stream and that of the boat in still water.

Answer 1

Answer:

this problem will not solve because only one pair of linear equation forms

Answer 2

Answer:

Speed of stream = 3 km/h

Speed of boat in still water = 8 km/h

Step-by-step explanation:

Let the speed of stream be y km/h and boat be x km/h.

✏ Downstream:

Distance = 44 km

speed = (x + y) km/h

∴ time, t1 = distance/speed = 44/x + y

i.e., 4 = 44/x + y

∴ x + y = 11 → (1)

✏ Upstream:

Distance = 20 km

speed = (x - y) km/h

time, t2 = 20/x - y

i.e., 4 = 20/x - y

∴ x - y = 5 → (2)

Now, (1) + (2) ⇒

⇝ 2x = 16

⇝ x = 16/2

⇝ x = 8

Substituting the value of x in (1) ⇒

⇝ 8 + y = 11

⇝ y = 11 - 8

⇝ y = 3

$\:$

i.e., speed of stream = 3 km/h

speed of boat in still water = 8 km/h