SOLUTION: it takes 15 workers to build 500 feet of fencing in 6 hours. At this rate, how many workers are needed to build 1000 feet of fencing in 9 hours

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Question 224981: it takes 15 workers to build 500 feet of fencing in 6 hours. At this rate, how many workers are needed to build 1000 feet of fencing in 9 hours
Found 2 solutions by josmiceli, Edwin McCravy:
Answer by josmiceli(19441) About Me  (Show Source):
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it takes 15 workers to build 500 feet of fencing in 6 hours.
Therefore, 1 worker would take 6%2A15+=+90 hours to build
500 feet of fencing
The 1 worker would take 9 hours to build 50 feet of fencing
2 workers would take 9 hours to build 100 feet of fencing
20 workers would take 9 hours to build 1000 feet of fencing
check:
working backwards,
1 worker would take 9 hours to build 50 feet of fencing
OK

Answer by Edwin McCravy(20066) About Me  (Show Source):
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it takes 15 workers to build 500 feet of fencing in 6 hours. At this rate, how many workers are needed to build 1000 feet of fencing in 9 hours
It takes 15 workers to build 500 feet of fencing in 6 hours. 

Doubling the workers doubles the fencing in the same time.  Therefore,

it takes 30 workers to build 1000 feet of fencing in 6 hours.

Doubling the workers halves the time for the same amount of fencing. Therefore,

It takes 60 workers to build 1000 feet of fencing in 3 hours.

Using only one-third as many workers triples the time for the same
amount of fencing. Therefore,

It takes 20 workers to build 1000 feet of fencing in 9 hours.

Edwin