Hello, I'm having trouble working with this problem:
A capentry work can be done in 3 days by 12 persons. If 9 persons work on the same task, how long would it take them to finish it?
The correct answer is 4, but I don't understand how to get it.
I thought I had to do: 9 x 3 / 12, but it's not correct.
How can I solve this?
Thanks
Assuming every one works at the same rate, the each is working at a rate of (1/12) job in 3 days or 1/36 job per day. 9 people will work at 9/36= 1/4 job per day and so 4/1= 4 day per job: 4 days to do the job.
By the way: your answer, 9 x 3/12= 27/12 is slightly larger than 2 days and so less than 3 days. You are saying that 9 people can do the job faster than 12 people! That should hae told you that you should have divided where you
multiplied.