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Ten painters working 8 hours daily take 15 days to paint 3 houses of 4 rooms each. How many painters working 6 hours daily for 25 days will be required to paint 12 houses of 3 rooms each?
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This problem is the-rate-of-work problem, and the equation is an equality of rate-of-work for both cases.
Rate of work in the first case is
.
Rate of work in the second case is
.
So, an equation is
= ,
assuming that the rooms are identical and rate-of-work of each painter is the same.
Solve this equation to find x, the number of painters required for the second case.