SOLUTION: If it takes 3 people 4 hours to paint a room. How long will it take 2 people to paint the same room?

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Question 721140: If it takes 3 people 4 hours to paint a room. How long will it take 2 people to paint the same room?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming each person works at an equal rate, the rates are additive when they work together. Let r be the rate at which any one worker works. 3r%2A4=1, or 3%2A4 is that one job in the 4 hour time period.

3r%2A4=1
3r%2A4%2F3=1%2F3
r%2A4=1%2F3
r%2A4%2F4=1%2F%283%2A4%29
highlight%28r=1%2F12%29 The Rate of ONE worker.

How long for TWO workers together to do the job?
Together , their combined rate is 1%2F12%2B1%2F12=1%2F6 jobs per hour, ... OR...
6 hours to paint the room (one job).