Question

It takes 12 people 15 hours to complete and certain job.how many hours would it take 18 people, working at the same rate to complete 2/5 of the same job?

Answer 1

9 hours

Explanation:

12 people take 15 hours to complete one job. First let's ask how long it would take 18 people working at the same rate to complete the same job? We can use proportions to answer this

`(12 people)/(15 hours) = (18 people)/(x hours)\\x = (18*15)/(12) = 22.5`

Now we know that one job takes 18 people 22.5 hours, so 2/5 of the job would take

`(18*15)/(12) * (2)/(5) = 9`