Question

Первая бригада может выполнить задание за 21 час а вторая за 28 часов. За сколько часов совместной работы они могут выполнить Это задание?

Answer 1

1- весь объем работ
1:21=1/21 раб/ч скорость работы 1й бригады
1:28=1/28 раб/ч скорость работы 2й бригады
1/21+1/28=4/84+3/84=7/84=1/12 раб/ч совместная скорость работы обеих бригад
1:1/12=1*12/1=12 часов им понадобится

Answer 2

Calculation of Combined Work Time

To determine the amount of time it would take for the first and second brigades to complete the task together, we need to calculate their combined work rate.

Let's assume that the first brigade's work rate is represented by x (in tasks per hour) and the second brigade's work rate is represented by y (in tasks per hour).

According to the information provided, the first brigade can complete the task in 21 hours, which means their work rate is 1 task per 21 hours. Similarly, the second brigade can complete the task in 28 hours, so their work rate is 1 task per 28 hours.

To find the combined work rate, we can add the individual work rates together. Therefore, the equation becomes:

x + y = 1/21 + 1/28

Now, we need to solve this equation to find the combined work rate.

Let's calculate it step by step:

1. Convert the fractions to a common denominator:

x + y = (4/84) + (3/84) Simplifying the fractions: x + y = 7/84

2. Simplify the equation:

x + y = 1/12

Now, we know that the combined work rate of the two brigades is 1 task per 12 hours.

To find the time it would take for them to complete the task together, we can use the formula:

Time = 1 / Combined Work Rate

Substituting the value of the combined work rate:

Time = 1 / (1/12)

Simplifying the expression:

Time = 12 hours

Therefore, it would take the first and second brigades 12 hours to complete the task together.