SOLUTION: if 15 labours can construct a 30 meter wall in 20 days.how many labours will be required to construct a 20 meter wall in 30 days?

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Question 722079: if 15 labours can construct a 30 meter wall in 20 days.how many labours will be required to construct a 20 meter wall in 30 days?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Focus on how many meters per day. 15 workers do 30 meters in 20 days. That is 3/2 meters per day, if 15 workers are active together. ONE single worker is only 1/15 that rate. ONE worker operates at %281%2F15%29%283%2F2%29=3%2F%2815%2A2%29 meters per day.

Simplified, any one individual worker operates at 1%2F10 meters per day.

1 laborer in 30 day, does 3 meters.
2 laborers in 30 days, does 6 meters.
3 laborers in 30 days, does 9 meters.
4 laboreres in 30 days, does 12 meters.
5,.........................15 meters.
6,.........................18 meters
7,.........................21 meters.

The method seems good but there must be a mistake, since I'm finding a noninteger value for number of laborers. The solution here seems to be, use 7 laborers and the 20 meters will take slightly less than 30 days. Maybe another tutor can catch where I went wrong.