SOLUTION: Working together, 4 skilled workers can complete a job in 5 days. However, 5 semi-skilled workers can complete the same job in 6 days. If 1 semi-skilled and 2 skilled workers work

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Working together, 4 skilled workers can complete a job in 5 days. However, 5 semi-skilled workers can complete the same job in 6 days. If 1 semi-skilled and 2 skilled workers work       Log On


   



Question 729260: Working together, 4 skilled workers can complete a job in 5 days. However, 5 semi-skilled workers can complete the same job in 6 days. If 1 semi-skilled and 2 skilled workers work together, how long does it take for them to complete the same job?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Working together, 4 skilled workers can complete a job in 5 days.
therefore: 4 * 5 = 20 man-days for skilled men complete the job
:
However, 5 semi-skilled workers can complete the same job in 6 days.
therefore: 5 * 6 = 30 man-days for semi-skilled men to complete the job
:
If 1 semi-skilled and 2 skilled workers work together, how long does it take for them to complete the same job?
Let d = number of days for them to complete the job.
Let the completed job = 1,
Each group will do a fraction of the job, the two fractions add up to 1
:
%282d%29%2F20 + %281d%29%2F30 = 1
multiply by 60, resulting in:
3(2d) + 2(1d) = 60
6d + 2d = 60
8d = 60
d = 60/8
d = 7.5 days for them to complete the job together