The boat traveled 96 km downstream in 4 hours. What does the boat need for the return trip if the speed is 4 km / h?

The boat will sail back against the current.

Let’s calculate the distance that the boat helped to swim the currents:

1) 4 km / h * 4 hours = 16 km.

Now let’s calculate the distance that the boat sailed without the current:

2) 96 km – 16 km = 80 km.

Next, let’s calculate the boat’s own speed by dividing the distance by the time:

3) 80 km / 4 hours = 20 km / h.

Let’s calculate the speed of the boat against the current:

4) 20 km / h – 4 km / h = 16 km / h.

Now we can calculate the time it will take for the boat to return:

5) 96 km / 16 km / h = 6 hours.