SOLUTION: A box contains 6 white balls, 7 black balls, and 5 red balls. How many red balls must be added to the box so that probability of drawing a red ball is 6/7?

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Question 1016501: A box contains 6 white balls, 7 black balls, and 5 red balls. How many red balls must be added to the box so that probability of drawing a red ball is 6/7?
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
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x=red balls to add
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x%2F%286%2B7%2B5%2Bx%29=6%2F7
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x%2F%2818%2Bx%29=6%2F7 Cross multiply.
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7x=6%28x%2B18%29
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7x=6x%2B108
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x=108
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ANSWER: Add 108 red balls.
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