SOLUTION: One secretary can do a particular typing job in 6hr and another secretary can do same job in 4hr. How long will it take if the job is done by the two secretaries working together?

Question 507800: One secretary can do a particular typing job in 6hr and another secretary can do same job in 4hr. How long will it take if the job is done by the two secretaries working together?
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
One secretary can do a particular typing job in 6hr and another secretary can do same job in 4hr. How long will it take if the job is done by the two secretaries working together?
.
Let x = time (hours) it takes for both
then
x(1/6 + 1/4) = 1
multiply both sides by 12 (common denominator):
x(2 + 3) = 12
x(5) = 12
x = 12/5
x = 2.4 hours
or
x = 2 hours and 24 minutes

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