SOLUTION: A manager on the job recognizes that he needs a computer task accomplished within 3.5 hours. Through observation he chooses his best employee (employee 1), and 2 others to work tog

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Question 869525: A manager on the job recognizes that he needs a computer task accomplished within 3.5 hours. Through observation he chooses his best employee (employee 1), and 2 others to work together to accomplish this. He knows that employee 1 can complete the task in 9 hours working alone. While the others can complete the task in 12 hours and 13 hours, respectively, working alone. How long will it take the 3 employees working together to complete the computer task? Round your answer to 1 decimal place.
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
These are each employee's work rates, in JOBS per HOUR:
Employee 1, 1%2F9
Employee 2, 1%2F12
Employee 3, 1%2F13

The combined rate of the three employees working together is the sum of their individual rates.

1%2F9%2B1%2F12%2B1%2F13 jobs per hour; but you will want the reciprocal, which will be in hours per job.

The final meaning that you are looking for is 1%2F%281%2F9%2B1%2F12%2B1%2F13%29 HOURS per JOB.