Question

От двух пристаней на встречу друг другу одновременно отчалили лодка и теплоход.Собственная скорость лодки -10,8 км / ч.Лодка двигалась по течению реки ,а теплоход-30,2 км/ч,двигался против течения .Через сколько часов после начала движения они встретятся, если расстояние между пристанями -205 км

Answer 1

30,2-10,8=19,4
10,8+19,4=30,2
205/30,2=6  119/151

Answer 2

Problem Analysis

We are given that a boat and a steamboat depart simultaneously from two piers to meet each other. The boat has a speed of -10.8 km/h (moving against the current), and the steamboat has a speed of 30.2 km/h (moving against the current). The distance between the piers is 205 km. We need to find out how many hours it will take for them to meet.

Solution

To solve this problem, we can use the formula: time = distance / relative speed.

Let's calculate the relative speed of the boat and the steamboat. Since the boat is moving against the current, we need to subtract the speed of the current from its speed. The steamboat is moving against the current, so we need to add the speed of the current to its speed.

The relative speed of the boat is -10.8 km/h (boat speed) - x km/h (current speed), where x is the speed of the current.

The relative speed of the steamboat is 30.2 km/h (steamboat speed) + x km/h (current speed).

Since the boat and the steamboat are moving towards each other, we can add their relative speeds to get the total relative speed.

Let's solve for x using the given information.

Calculation

Relative speed of the boat + relative speed of the steamboat = total relative speed

-10.8 km/h - x km/h + 30.2 km/h + x km/h = total relative speed

Simplifying the equation, we get:

19.4 km/h = total relative speed

Now, we can calculate the time using the formula: time = distance / relative speed.

time = 205 km / 19.4 km/h

Answer

The boat and the steamboat will meet after approximately 10.57 hours.

Note: The answer is rounded to two decimal places.

Explanation

The boat and the steamboat will meet after approximately 10.57 hours. This means that after 10.57 hours from the start of their journey, they will be at the same location.

To calculate this, we first found the relative speed of the boat and the steamboat. The relative speed of the boat is -10.8 km/h (boat speed) minus the speed of the current, and the relative speed of the steamboat is 30.2 km/h (steamboat speed) plus the speed of the current.

By adding the relative speeds of the boat and the steamboat, we found the total relative speed, which is 19.4 km/h.

Finally, we divided the distance between the piers (205 km) by the total relative speed (19.4 km/h) to find the time it takes for them to meet, which is approximately 10.57 hours.

Please let me know if you need any further clarification.