Question 1188646: Maria can weed 1,000 m² of cogonal farm surface in 40 hours, while her brother, Bryant, can do the same amount of work in 20 hours. If they work together, how long will it take them to weed one hectare (10,000 m2) of cogonal land surface?
Found 3 solutions by Shin123, MathTherapy, ikleyn:
Answer by Shin123(626)   (Show Source):
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
Maria can weed 1,000 m² of cogonal farm surface in 40 hours, while her brother, Bryant, can do the same amount of work in 20 hours. If they work together, how long will it take them to weed one hectare (10,000 m2) of cogonal land surface?
As she takes 40 hours to do the entire job (weed 1,000 m²), Maria's per hour rate = 
As the brother takes 20 hours to do the entire job (weed 1,000 m²), the brother's per hour rate = 
With time that it takes both to do 1 job (1,000 m²) being T, we get: 
T + 2T = 40 ------ Multiplying by LCD, 40T
3T = 40
Time taken by both to do 1 job (1,000 m²), or 
Time taken by both to do 10 SUCH jobs (weed 10,000 m²) = 
Answer by ikleyn(52793)  (Show Source):
You can put this solution on YOUR website! .
It is, actually, pure Arithmetic problem.
It can be solved without Algebra and without using equations.
It is actually, arithmetic problem for very young students/children of 4-th grade level,
who just know arithmetic, but are not familiar with Algebra and with equations.
Therefore, a preferable method to solve it is using Arithmetic only, without Algebra.
It is how this problem is intended and designed, and how it is expected to be solved.
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