Aboat goes 50 km downstream in the same time that it takes to go 30 km upstream. the speed of the stream is 3km/hour. find the speed of the boat in still water.

The speed of the boat in still water is 12 km/hour.

Step-by-step explanation:

Given:

Boat goes 50 km downstream and 30 km upstream. The speed of the stream 3 km/hour.

Now, to find the speed of the boat in still water:

Let the speed of boat in still water be .

The speed of the downstream be

And, the speed of the upstream be

And, now we find the time by putting the formula:

So, downstream time is:

So, upstream time is:

According to question:

Time upstream = Time downstream

By cross multiplication:

By taking variables in one side and taking numbers on the other side we get:

Dividing both sides by 20 we get :

Therefore, the speed of the boat in still water is 12 km/hour.

256π units²   (answer b)

step-by-step explanation:

the formula for the surface area of a sphere of radius r

is             a = 4πr²

and so, if r = 8 units, then the surface area is:

a = 4π(8 units)² = 256π units²   (answer b)

darn right!

step-by-step explanation:

steve kerr's sons name is let that skin in.