The amount of work, W, accomplished in time, T, depends on the rate, R, at which the work is being accomplished. Work problems are quite similar to the problems of uniform motion. The equation we use is
W = RT
Try to solve the question by determining the rate per time period (usually per hour or per minute). The rate, R, is most often expressed as the job to do divided by the time, where W usually equals one completed job.
Examples of
Work Questions
A tractor plows 1/10 of a field each hour; the job is one field, so the rate is 1/10 of a field per hour.
If it takes x tractors to do one job in 1 hour, then each tractor works at a rate of 1/x of the job per hour.
If it takes x tractors 4 hours to do one job, then each tractor works at one quarter of the previous rate, or at the rate of 1/4x of the job per hour.
In general, if it takes x tractors y hours to do one job, the rate that each tractor works is 1/(x × y) of the job per hour.
Example 1
It takes 3 men 8 hours to paint a house. How long will it take 5 men to paint the same house?
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