"10 men can paint 30 houses in 60 days and 5 men can paint 15 house in how many days"
There are several ways to get to the answer. The simplest way here
is that for half the workers to paint half the number of houses would
take the same amout of time, which is 60 days.
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Or here's another way:
10 men can paint 30 houses in 60 days,
therefore 1 man can paint 3 houses in 60 days;
therefore 1 man can paint 15 houses in 300 days;
therefore 5 men can paint 15 houses in 60 days.
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Still another way is to use the worker-jobs-time formula
W1 = number of workers in the first situation
T1 = time required in the first situation
J1 = number of jobs done in the first situation
W2 = number of workers in the second situation
T2 = time required in the second situation
J2 = number of jobs done in the second situation
The formula is
Edwin