Question

Первая бригада может выполнить задание за 21 часа , а вторая за 28 ч . Какую часть задания выполнят бригады за 1 час совместной работы ?

Answer 1

1) 1 : 21 = 1/21 часть задания выполняет первая бригада за 1 час

2) 1 : 28 = 1/28 часть задания выполняет вторая бригада за 1 час

3) 1/21 + 1/28 = (4 + 3)/84 = 7/84 часть задания выполнят обе бригады за 1 час

4) 1 : 7/84 = 1 * 84/7 = 12 часов

Ответ: за 12 часов совместной работы бригады выполнят задание

Answer 2

Task Completion Rate for Two Brigades

To determine the portion of the task completed by two brigades working together in one hour, we need to calculate the combined work rate of the two brigades.

Let's assume that the first brigade can complete the task in 21 hours, while the second brigade can complete it in 28 hours.

To find the combined work rate, we can calculate the reciprocal of the time taken by each brigade to complete the task. The work rate is inversely proportional to the time taken.

The work rate of the first brigade is 1/21 of the task per hour, while the work rate of the second brigade is 1/28 of the task per hour.

To find the combined work rate, we add the work rates of the two brigades:

1/21 + 1/28 = 49/588 + 42/588 = 91/588

Therefore, the combined work rate of the two brigades is 91/588 of the task per hour.

To find the portion of the task completed by the two brigades in one hour, we divide the combined work rate by the total work rate of the task, which is 1:

(91/588) / 1 = 91/588

Therefore, the two brigades will complete 91/588 of the task in one hour of working together.

Please note that the above calculation assumes that the work rates of the brigades remain constant throughout the task and that there are no other factors affecting their efficiency.