Question

От двух пристаней расстояние между которыми 140 км,одновременно навстречу друг другу отправились моторная лодка и катер и встретились через 2 часа.скорость катера 45 км/ч.найди скорость моторной лодки

Answer 1

140:2=70(км/ч)- общая скорость 70-45=25(км/ч)- скорость моторной лодки, Или  можно решить и так:   45*2=90 км проплыл катер 140-90=50(км )-проплыла лодка 50:2-25 (м/ч)- скорость лодки 

Answer 2

Problem Analysis

We are given that the distance between two piers is 140 km. A motorboat and a speedboat start simultaneously from these piers and meet each other after 2 hours. We are also given that the speed of the speedboat is 45 km/h. We need to find the speed of the motorboat.

Solution

Let's assume the speed of the motorboat is x km/h.

To find the speed of the motorboat, we can use the formula: Speed = Distance / Time.

The time taken by both the motorboat and the speedboat to meet each other is 2 hours.

The distance covered by the motorboat in 2 hours can be calculated using the formula: Distance = Speed × Time.

The distance covered by the speedboat can also be calculated using the same formula.

Since the total distance between the piers is 140 km, the sum of the distances covered by the motorboat and the speedboat should be equal to 140 km.

Let's calculate the distance covered by the motorboat and the speedboat and set up an equation to solve for the speed of the motorboat.

Calculation

Distance covered by the motorboat = Speed of the motorboat × Time = x × 2 km

Distance covered by the speedboat = Speed of the speedboat × Time = 45 × 2 km

According to the problem, the sum of the distances covered by the motorboat and the speedboat is equal to 140 km.

So, we have the equation: x × 2 + 45 × 2 = 140.

Simplifying the equation, we get: 2x + 90 = 140.

Subtracting 90 from both sides of the equation, we get: 2x = 50.

Dividing both sides of the equation by 2, we get: x = 25.

Therefore, the speed of the motorboat is 25 km/h.

Answer

The speed of the motorboat is 25 km/h.

Verification

Let's verify the answer using the given information.

The distance covered by the motorboat in 2 hours is 25 × 2 = 50 km.

The distance covered by the speedboat in 2 hours is 45 × 2 = 90 km.

The sum of the distances covered by the motorboat and the speedboat is 50 + 90 = 140 km, which is equal to the total distance between the piers.

Therefore, the answer is verified.