Question

Find the speed of stream if a boat covers 36 km in downstream in 6 hours which is 3 hours less in covering the same distance in upstream?

A) 1.5 kmph B) 1 kmph C) 0.75 kmph D) 0.5 kmph

Answer 1

Answer:

B. 1 km/h

Step-by-step explanation:

Let the speed of the boat in still water be x km/hr and the speed of the stream be y km/hr. This means that the boat travels downstream at a speed of x+y km/hr and upstream at a speed of x-y km/hr.

According to given conditions the boat travels 36 km downstream in 6 hours. Since speed=distance/time, the boat travels downstream at a speed of 36/6 km/hr = 6km/hr. But we know that the boat travels downstream at a speed of x+y km/hr. Therefore x+y=6. This is our first equation.

Similarly for the journey upstream the boat took 6+3 hours = 9 hours. Therefore 36 km / 9 hours = x-y km/hr. This gives us x-y=4 as our second equation.

Adding both equations we get: x+y+(x-y) = 6+4 which implies that 2x=10 and thus x=5. Substituting x=5 in the first equation, we get 5+y=6, thus y=1.

Therefore, the speed of the stream is 1 km/hr.

Hope it helps you.

Thanks

Answer 2

Answer:

Given :-

Distance = 36km (downstream)

Time = 6hours

Time in upstream = 6+3 = 9hours.

To find :- Find speed of stream!!

Solution :-

Downstream = x+y

Upstream = x-y

Speed in downstream :-

distance/time = 36/6 = 6km/h

as known x+y = downstream

therefore, x+y = 6 -----> 1.

Similarly for upstream!!

Speed = 36/9 = 4

therefore, x-y = 4 ------> 2.

Using elimination method in 1 and 2 eqn. we get,

2x = 10

x = 5

Substituting x = 5 in 1eqn

we get, 5+y = 6, y = 1

Therefore the speed of boat is 1km/h.

~ Nikhra❤️