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and conclude that ? = 50 days. You conclude ? = 50 in order that the numerator and denominator have the same value, that is
The units "workers × job × days" don't make sense to me but in the equation above "1 job" appears on both sides so I can cancel it and get
Now the units make sense to me. The statement you started with "ten workers perform one job in five days" can be restated as "one job takes 10 × 5 = 50 workerdays" where a workerday is the amount of work that one worker can accomplish in one day. Now it's clear that one worker will require 50 days to complete the job. At the same rate if you have 4 jobs to complete that will take 4 × 50 = 200 workerdays and thus with 10 workers will require 20 days. I hope this helps, Kenneth replied I have a followup question to ask. In you reply you indicated the following: 'The units "workers × job × days" don't make sense to me' I thank you for your followup reply, and for your first reply. I did find it helpful!
Kenneth, What I meant was that I didn't see how the product workers × job × days had any relevance to the problem. I didn't immediately see why you were getting the correct answer form this calculation. The key was your question "..why the number representing the jobs in this calculation needs to be the same in the group of factors in both the numerator and in the denominator in order to provide the correct answer?" If the number of jobs is the same in both the numerator and denominator then you can cancel the job number and then the product is workers × days. This I saw does have relevance to the problem as I explained in my earlier response. I hope this helps,  


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