Rates

[KWF]

Here is my question:

15 workers can finish a job in 7 days.

If I want to find the number of days 21 workers can finish the job, the calculation becomes 1/(21 workers) X 15 workers X 7 days.

If the 21 and 15 are reduced to 5 and 7 and the calculation becomes 1/7 X 5 X 7 days, what do these two reduced terms (7 and 5) indicate or represent?

Do they represent 5 workers and 7 workers, as in (1/7 worker) X 5 workers X 7 days = 5 days?

 

[KWF]

Here is my question:

15 workers can finish a job in 7 days.

If I want to find the number of days 21 workers can finish the job, the calculation becomes 1/(21 workers) X 15 workers X 7 days.

If the 21 and 15 are reduced to 5 and 7 and the calculation becomes 1/7 X 5 X 7 days, what do these two reduced terms (7 and 5) indicate or represent?

Do they represent 5 workers and 7 workers, as in (1/7 worker) X 5 workers X 7 days = 5 days?

Denis:

Thanks for your reply!

Does the following make sense in regards to my question?

The 5 and 7 represent nothing of the original equation. I have simply reduced 15/21 to make the equation easier to solve.

 

[KWF]

Denis:

Thanks for your reply!

Does the following make sense in regards to my question?

The 5 and 7 represent nothing of the original equation. I have simply reduced 15/21 to make the equation easier to solve.

And also,

I cannot get your calculation to equal 1/5. Is it 1/7 divided by (21 X 15)? This equal 45.

This calculation equals 1/5: 1/7 X 21/15 = 1/5

 

[KWF]

1 day: 15 workers = 1/7 of job
1 day: 21 workers = p of job

p = (1/7) / 15 * 21 = 1/5

Your 5 and 7 are irrelevant.

Hello Denis:

How does the calculation p = (1/7) / 15 * 21 = 1/5 derive from the following?

1 day: 15 workers = 1/7 of job
1 day: 21 workers = p of job

 

[KWF]

Denis

How does the calculation p = (1/7) / 15 * 21 = 1/5 derive from the following?

1 day: 15 workers = 1/7 of job
1 day: 21 workers = p of job

p = (1/7) / 15 * 21 = 1/5