The boat traveled 10 km against the current, and then 45 km along the current, spending 2 hours

| September 2, 2021 | education

The boat traveled 10 km against the current, and then 45 km along the current, spending 2 hours for the entire journey. find your own speed of the boat if the river speed is 5 km / h.

To solve this problem, we introduce the conditional variable “X”, through which we denote the boat’s own speed.

Then, based on the data of the problem, we will compose the following equation: 10 / (X – 5) + 45 / (X + 5) = 2.

Solving this equation, we get the quadratic equation 2X ^ 2 – 55X +125 = 0.

Solving the quadratic equation, we get two positive roots X1 = 2.5 kilometers per hour and X2 = 25 kilometers per hour.

Since the boat’s own speed cannot be less than the speed of the river, the correct answer would be 25 kilometers per hour.

Answer: 25 kilometers per hour.



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