The speed of the river flow is 2.2 km / h, the boat departed from the pier and went along the river.

| February 1, 2021 | education

The speed of the river flow is 2.2 km / h, the boat departed from the pier and went along the river. After 1.5 hours, it turned back, went against the current, 5 hours and stopped. At what distance from the pier it stopped.

Let’s take the speed of the boat as X. Then, if he swam with the current, his speed increased by the speed of the current, and therefore in 1.5 hours he swam: (2.2 + X) * 1.5.
The boat sailed against the current for 0.5 hours, its speed decreased by the speed of the current, so it sailed: (X – 2.2) * 0.5.

The distance from the pier is defined as the difference between how much the boat has sailed with the current and against the current:
(2.2 + X) * 1.5 – (X – 2.2) * 0.5 = 2.2 * 1.5 + X * 1.5 – X * 0.5 + 2.2 * 0, 5 = X + 4.4.

Answer: The boat stopped at a distance that it sails in an hour, excluding the river speed, + 4.4 km.



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