To travel 60 km against the river and 54 km in still water, the steamer needs 4 hours and 30 minutes.
To travel 60 km against the river and 54 km in still water, the steamer needs 4 hours and 30 minutes. To overcome 162 km in stagnant water, the steamer needs 3 hours more time than to overcome 72 km upstream of the same river. Find your own steamer speed and current speed
Let the own speed of the steamer be x km / h, and the speed of the river flow y km / h.
Then the steamer moves against the stream of the river at a speed of (x – y) km / h.
By condition:
60 / (x – y) + 54 / x = 4.5;
162 / x = 3 + 72 / (x – y).
Divide the second equation by 3:
54 / x = 1 + 24 / (x – y).
Let’s substitute in the first:
60 / (x – y) + 1 + 24 / (x – y) = 4.5;
84 / (x – y) = 3.5;
84 = 3.5 * (x – y);
x – y = 24.
Substitute this value into the second equation:
54 / x = 1 + 24/24;
54 / x = 1 + 1;
54 / x = 2;
x = 54: 2;
x = 27 (km / h) – the boat’s own speed.
27 – y = 24;
y = 27 – 24;
y = 3 (km / h) – the speed of the river.
Answer: the boat’s own speed is 27 km / h, the speed of the river is 3 km / h.