Question 173203This question is from textbook Introductory Algebra
: Frank can type a report in 3 hours and James takes 4 hours. How long will it take the two of them typing together?
This question is from textbook Introductory Algebra
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Frank can type a report in 3 hours and James takes 4 hours. How long will it take the two of them typing together?
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You have to use the inverses.
Frank does 1/3 of the report in an hour. James does 1/4 per hour.
Together, they do 1/3 + 1/4 = 7/12 per hour, so it takes 12/7 hours.
A shortcut is the product/sum:
3*4/(3+4) = 12/7
It works for 2 elements, not 3 or more.
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