A certain fish requires 3 hrs to swim 15km downstream. The return trip upstream takes 5 hrs. What is the speed of the fish still in water? How fast is the current of the stream?

downstream = 15/3 = 5 km/hr

upstream = 15/5 = 3 km/hr
so
v+c = 5
v-c = 3
---------- subtract
0 +2c = 2
c = 1 km/hr

ok

enter

stan Stray Kids :)

To find the speed of the fish still in water, let's assume the speed of the fish is 'x' km/h, and the speed of the current is 'y' km/h.

When swimming downstream, the fish is aided by the current, so its effective speed is x + y km/h. We are given that the fish takes 3 hours to cover a distance of 15 km downstream, so:

Distance = Speed × Time
15 km = (x + y) km/h × 3 hours

Similarly, when swimming upstream, the fish has to swim against the current, so its effective speed is x - y km/h. We are given that the fish takes 5 hours to cover a distance of 15 km upstream, so:

Distance = Speed × Time
15 km = (x - y) km/h × 5 hours

Now we have two equations with two variables. We can solve this system of equations to find the values of x and y.

Let's solve the first equation for x + y:
15 km = 3(x + y) km/h
Dividing both sides by 3:
5 km = x + y

Now, let's solve the second equation for x - y:
15 km = 5(x - y) km/h
Dividing both sides by 5:
3 km = x - y

We now have a system of equations:
5 km = x + y
3 km = x - y

Adding these two equations together, we eliminate the 'y' variable:
5 km + 3 km = (x + y) + (x - y)
8 km = 2x

Dividing both sides by 2:
4 km/h = x

So, the speed of the fish in still water is 4 km/h.

To find the speed of the current, we can substitute the value of x into one of the original equations. Let's use the first equation:

5 km = x + y
5 km = 4 km/h + y

Subtracting 4 km/h from both sides:
y = 5 km - 4 km/h
y = 1 km/h

Therefore, the speed of the current is 1 km/h.