The boat sailed from A to B in 10 hours, moving against the stream of the river. On the way back, the boat’s
The boat sailed from A to B in 10 hours, moving against the stream of the river. On the way back, the boat’s engine broke down and the last third of the way, it swam at the speed of the current. In total, the return journey took 14 hours. How long does it take to return with the engine running?
Let’s solve the problem through the equation. Let the speed of the boat be x km / h, and the speed of the current y km / h. Since the boat moved against the current for 10 hours, therefore, its speed was equal to x – y km / h, and the distance traveled was 10 * (x – y) km.
1/3 of the way is 10 * (x – y) / 3 km.
2/3 of the way – 20 * (x – y) / 3 km.
Downstream speed – x + y km / h.
Time spent on movement:
10 * (x – y) / 3 / y + 20 * (x – y) / 3 / (x + y) = 14;
10 * (x – y) * (x + y) + 20 * y * (x – y) = 14 * 3 * y * (x + y).
10 * x * x – 10 * y * y + 20 * x * y – 20 * y * y = 42 * x * y + 42 * y * y.
10 * x * x – 72 * y * y – 22 * x * y = 0.
5 * x * x – 36 * y * y – 11 * x * y = 0.
There is not enough data in the tasks.