Question

одна бригада может выполнить задание за 9 дней а другя за 12 дней первая бригада проработала 3 дня а потом вторая завершила работу.за сколько дней было выполнено задание

Answer 1

Problem Analysis

We are given that one brigade can complete a task in 9 days, while another brigade can complete the same task in 12 days. The first brigade worked for 3 days, and then the second brigade completed the task. We need to determine how many days it took to complete the task.

Solution

To solve this problem, we can calculate the work done by each brigade and then determine the total time required to complete the task.

Let's assume that the total work required to complete the task is represented by the variable "W". Since the first brigade can complete the task in 9 days, their work rate can be represented as "W/9" per day. Similarly, the second brigade's work rate can be represented as "W/12" per day.

Since the first brigade worked for 3 days, they completed a total of "3 * (W/9)" work. The remaining work that needs to be done can be calculated as "W - 3 * (W/9)".

Now, the second brigade completes the remaining work. We can set up the equation:

"3 * (W/9) + x * (W/12) = W"

Here, "x" represents the number of days taken by the second brigade to complete the remaining work.

Simplifying the equation, we get:

"3W/9 + xW/12 = W"

Multiplying both sides by 36 to eliminate the denominators, we get:

"4W + 3xW = 36W"

Simplifying further, we get:

"4 + 3x = 36"

Solving for "x", we find:

"x = 32/3"

Therefore, the second brigade took approximately 10.67 days to complete the remaining work.

To find the total number of days required to complete the task, we add the 3 days worked by the first brigade to the 10.67 days taken by the second brigade:

"3 + 10.67 = 13.67"

Therefore, the task was completed in approximately 13.67 days.

Answer

The task was completed in approximately 13.67 days.