From pier A to pier B, the raft departed 28.8 km between them. After 0.4 hours

| April 28, 2021 | education

From pier A to pier B, the raft departed 28.8 km between them. After 0.4 hours, a boat came out of the pier B to meet him, its own speed is 17.5 km / h, and met the raft after 1.6 hours. Find the speed of the river.

Let’s write down the speed of the river as x km / h.

The speed of the current is the speed of the raft, so in 0.4 hours it passed; 0.4 * x.

The speed of the boat upstream of the river will be:

17.5 – x km / h.

The distance that was between the boat and the raft at the time the boat left was:

28.8 – 0.4 * x.

The speed of convergence between the raft and the boat is:

x + (17.5 – x) = 17.5 km / h.

We get the equation:

1.6 * 17.5 + 0.4 * x = 28.8.

28 + 0.4 * x = 28.8.

0.4 * x = 0.8.

x = 0.8 / 0.4 = 2 km / h.

Answer:

The speed of the river is 2 km / h.



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