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Math Help - Time to analyze Sally and John painting a house

  1. #1
    TWN
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    Time to analyze Sally and John painting a house

    If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

    The answer is 2 hours and 24 minutes. How would one do the math to figure this out?
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  2. #2
    Flow Master
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    Quote Originally Posted by TWN View Post
    If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

    The answer is 2 hours and 24 minutes. How would one do the math to figure this out?
    In 1 hour Sally paints 1/4 of a house. In 1 hour John paints 1/6 of a house. Therefore (1/4 + 1/6) = ....... of a house gets painted in 1 hour by both of them. Therefore ....
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  3. #3
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    If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

    The answer is 2 hours and 24 minutes. How would one do the math to figure this out?
    Sally uses 4 hours (240 min) to paint a house. John uses 6 hours (360 min) to paint a house. Hence, in one min, they have painted (1/240 + 1/360) of the house. Hence, they used a total of 2 hours and 24 min (144 min) to paint the house.
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