Question

Помогите решить задачу первая бригада может выполнить задачу за21ч а вторая за 28ч за сколько часов совместной работы они могут выполнить это задание???

Answer 1

1) 1/21 + 1/28 = 28/588 + 21/588 = 49/588 = 1/12 общая производительность
2) 1 : 1/12 = 1 * 12 = 12 часов
За 12 часов выполнят работая вместе

Answer 2

Problem Analysis

We are given that the first team can complete a task in 21 hours and the second team can complete the same task in 28 hours. We need to determine how many hours it will take for both teams to complete the task together.

Solution

To solve this problem, we can use the concept of work rates. The work rate of a team is defined as the amount of work it can complete in one hour.

Let's assume that the work rate of the first team is x units of work per hour, and the work rate of the second team is y units of work per hour.

We know that the first team can complete the task in 21 hours, so their work rate can be calculated as 1/21 units of work per hour. Similarly, the work rate of the second team can be calculated as 1/28 units of work per hour.

When both teams work together, their work rates are additive. So the combined work rate of both teams is x + y units of work per hour.

We need to find the time it takes for both teams to complete the task together. Let's assume this time is t hours.

According to the work rate formula, the amount of work done is equal to the work rate multiplied by the time:

Amount of work done = Work rate × Time

Since both teams are working together, the amount of work done by both teams is equal to the total work required to complete the task.

Let's assume that the total work required to complete the task is 1 unit.

Using the work rate formula, we can write the equation:

1 = (x + y) × t

We can rearrange this equation to solve for t:

t = 1 / (x + y)

Substituting the work rates of the first and second teams, we get:

t = 1 / (1/21 + 1/28)

Simplifying this expression, we find:

t = 1 / (28/588 + 21/588) = 1 / (49/588) = 588 / 49 = 12 hours

Therefore, it will take both teams 12 hours to complete the task together.

Answer

The first team can complete the task in 21 hours, the second team can complete the task in 28 hours, and together they can complete the task in 12 hours.