Question

A boat takes 5 hours to go 300 km downstream. It takes the same time to go 150 km upstream. Calculate the speed of the boat in still water and the speed of the stream.

Answer 1

Answer: speed of the boat in still water is 45km/h

Speed of the stream is 15km/h

Step-by-step explanation: Answer:

Step-by-step explanation:Let the speed is boat is x km/h

and speed of the stream is y km/h

A/c to question, a boat takes 5 hours to go 300 km downstream.

So, speed of downstream = (x + y) km/h

So, 300/(x + y) = 5

x + y = 60.............(1)

Again, it takes same time to go 150 km upstream,

So, speed of upstream = (x - y) km/h

So, 150/(x - y) = 5

x - y = 30 .............(2)

Solve equations (1) and (2),

x = 45 km/h and y = 15 km/h

Hence,the speed of boat in still water is 45km/h and speed of stream is 15km/h.

Answer 2

Answer:

speed of the boat in still water = 45 km/hr and,

the speed of the stream  = 15 km/hr

Step-by-step explanation:

Let 'x' be the speed of boat in still water and 'y' be the speed of still water

The speed of upstream = x - y

The speed of down stream = x + y

It is given that,

1). A boat takes 5 hours to go 150 km upstream

Therefore upstream speed  = distance by time = 150/5 = 30

2).A boat takes 5 hours to go 300 km downstream

Therefore downstream speed  = distance by time = 300/55= 60

To find the x and y

We have,

x + y = 60   ----(1)

x - y  = 30 -----(2)

(1) + (2) ⇒ 2x = 90

x = 45 km/hr

y = 60  - 45 =15 km/hr

Therefore,

speed of the boat in still water x = 45 km/hr and,

the speed of the stream  y = 15 km/hr