The speed of the river flow is 5 km / h. The motor ship sailed downstream for 240 km in 8 hours.

| July 23, 2021 | education

The speed of the river flow is 5 km / h. The motor ship sailed downstream for 240 km in 8 hours. How much time does it need to spend on the return trip if the motor ship’s own speed has not changed?

The problem is solved in 4 steps.

In the first step, you need to find the speed of the ship along the river:

1) 240: 8 = 30 (km / h) – speed of the ship along the river.

In the second step, we find the own speed of the ship:

2) 30 – 5 = 25 (km / h) – own speed of the ship.

In the third step, you need to find the speed of the ship against the flow of the river:

3) 25 – 5 = 20 (km / h) – upstream of the river.

In the fourth step, we will find how much time it takes for the ship to spend on the return journey:

4) 240: 20 = 12 (h) – time for the return journey.

Answer: 12 hours.



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