<PRE><B>Question 1054311</B>
12 workers do 1/3 of a house in 15 days
in 1 day 12 workers do 1/45 of a house
1 worker does 1/540 of a house in a day, since 12 workers do 1/45th of a house (12/540)
want to know how many workers do 2/3 of a house in 18 days. Let the number = x.
18x/540=2/3 of a house. 18x is 18 days*x number of workers.
cross multiply
1080=54x
x=20
8 more workers must be added, since there are 12 to begin with.
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Check
12 workers can do 1/3 of a house in 15 days or the whole house in 45 days.
That means that there are 540 worker-days required to build the house.
12*15=180 worker days, the 1/3 of a house.
The 20 workers*18 days is 360 worker days, and that is 2/3 of the house.



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