Question

Моторная лодка за 3,5 часа проплыла 43,4Моторная лодка за 3,5 часа проплыла 43,4 км по течению реки и за 4,5 проплыла 39,6 км против течения. Найдите собственную скорость лодки и скорость течения

Answer 1

Надеюсь, что правильно)

Answer 2

Problem Analysis

We are given that a motorboat traveled 43.4 km downstream in 3.5 hours and 39.6 km upstream in 4.5 hours. We need to find the speed of the boat and the speed of the current.

Solution

Let's assume the speed of the boat is B km/h and the speed of the current is C km/h.

When the boat is traveling downstream, the effective speed is the sum of the boat's speed and the current's speed. So, the boat's effective speed downstream is B + C km/h.

Similarly, when the boat is traveling upstream, the effective speed is the difference between the boat's speed and the current's speed. So, the boat's effective speed upstream is B - C km/h.

We can use the formula speed = distance / time to calculate the boat's speed and the current's speed.

Calculation

Let's calculate the boat's speed and the current's speed using the given information.

Downstream: - Distance = 43.4 km - Time = 3.5 hours - Speed downstream = Distance / Time = 43.4 km / 3.5 hours = 12.4 km/h

Upstream: - Distance = 39.6 km - Time = 4.5 hours - Speed upstream = Distance / Time = 39.6 km / 4.5 hours = 8.8 km/h

Now, we have two equations: 1. B + C = 12.4 (equation 1) 2. B - C = 8.8 (equation 2)

Adding equation 1 and equation 2, we get: 2B = 21.2

Dividing both sides by 2, we find: B = 10.6

Substituting the value of B into equation 1, we can find the value of C: 10.6 + C = 12.4 C = 12.4 - 10.6 C = 1.8

Answer

The speed of the boat is 10.6 km/h and the speed of the current is 1.8 km/h.

Please let me know if I can help you with anything else.