The boat sails upstream for 1.4 km in 12 minutes. Find the speed of the current and the speed of the boat downstream

| January 3, 2021 | education

The boat sails upstream for 1.4 km in 12 minutes. Find the speed of the current and the speed of the boat downstream if the speed of the boat downstream is 1.3 times the speed of the boat upstream.

1. Let X km / h – boat speed in water, where there is no current.
And Y km / h is the current speed.
Then (X + Y) km / h is the speed downstream, (X – Y) – against.
2. The problem says that the boat moves 1.4 km, resisting the current, 12 minutes.
12 minutes = 0.2 hours.
1.4 / 0.2 = 14/2 = 7 km / h – speed.
3. Now determine the speed of the boat in the other direction.
7 * 1.3 = 9.1 km / h.
4. Then we get:
X + Y = 9.1.
X – Y = 7.
Let’s add two expressions.
2 * X = 16.1.
X = 8.05 km / h – boat speed.
Y = 9.1 – X = 9.1 – 8.05 = 1.05 km / h – current speed.
Answer: The speed of the boat is 8.05 km / h, the speed of the current is 1.05 km / h.



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