SOLUTION: Hannah and Lindsay clean an office. Hannah can clean the office alone in 3 hours. While Lindsay can in 2 hours. HOw long will it take them if they work together?

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Question 1008104: Hannah and Lindsay clean an office. Hannah can clean the office alone in 3 hours. While Lindsay can in 2 hours. HOw long will it take them if they work together?
Found 3 solutions by noahjavierwilliams43, ikleyn, cparks1000000:
Answer by noahjavierwilliams43(1) About Me  (Show Source):
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3 divided by 2= 1.5.
It will take Hannah and Lindsay together 1 1/2 hours to clean the office.

Answer by ikleyn(52803) About Me  (Show Source):
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.
The rate of Hanna is 1%2F3 of the office area per hour.
In other words, Hanna is cleaning 1%2F3 of the office area per hour.

The rate of Lindsay is 1%2F2 of the office area per hour.
In other words, Lindsay is cleaning 1%2F2 of the office area per hour.

Working together, they are cleaning 1%2F3 + 1%2F2 = 2%2F6 + 3%2F6 = 5%2F6 of the office area per hour.

Hence, it will take 6%2F5 of hour (or 1 hour and 12 minutes) for Hanna and Lindsay to clean the office if they work together.

For more solved problems on joint work see the lesson Using fractions to solve word problems on joint work in this site.


Answer by cparks1000000(5) About Me  (Show Source):
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Let x be the amount of office space that Hanna can clean in 1 hour and y be the amount of office space that Lindsay can clean in 1 hour. Let A be the surface area of the room. Then +2x+=+A+ and +3y+=+A+. Then let t be the time it takes Hanna and Lindsay too clean the room together. Then +t%28x%2By%29+=+A+.
Finally we solve for x and y in the equations not involving t then plug into the third equation to get:
+t%28+A%2F2+%2B+A%2F3+%29=+A
Then multiply through by 6%2FA to yield:
t%28+3+%2B+2+%29+=+6
Thus the time it takes for them to clean the room together is 1.2 hours which is 1 hour and 12 minutes.