Results 1 to 2 of 2

Math Help - multiplying ratios without knowing the ratios?

  1. #1
    Newbie
    Joined
    Sep 2009
    Posts
    3

    multiplying ratios without knowing the ratios?

    This problem is verbatim out of the text book.

    There is a number of balls in a jar. EAch ball is painted with at least one of twocolors, red or green. It is observed that 2/7 of the balls that have red color also have green color, while 3/7 of the balls that have green color also have red color. What fraction of the balls in the jar have both red and green colors?

    I understand that the numerator is some factor of seven, but the answer they give in the book makes no sense to me at all.

    I dont see how this can be solved without knowing the ratio of green to red, and I see the math in the book but it simply makes no sense to me.

    thanks in advance to anyone who can help
    Last edited by NotTooKeen; September 28th 2009 at 01:15 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,649
    Thanks
    1597
    Awards
    1
    Quote Originally Posted by NotTooKeen View Post
    There is a number of balls in a jar. EAch ball is painted with at least one of twocolors, red or green. It is observed that 2/7 of the balls that have red color also have green color, while 3/7 of the balls that have green color also have red color. What fraction of the balls in the jar have both red and green colors?
    Suppose that G is the number of balls having green on them.
    Suppose that R is the number of balls having red on them.
    Suppose that B is the number of balls having both colors on them.

    Now we are given that R = \frac{{7B}}{2}\;\& \,G = \frac{{7B}}{3}.
    The total number of balls is R+G-B.
    Using that we can get that the fraction of the balls in the jar have both red and green colors is \frac{6}{29}.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. ratios and trig ratios
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: November 7th 2011, 09:45 AM
  2. ratios
    Posted in the Algebra Forum
    Replies: 4
    Last Post: July 26th 2010, 06:39 AM
  3. Ratios?
    Posted in the Statistics Forum
    Replies: 2
    Last Post: June 28th 2010, 09:17 PM
  4. Ratios
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 25th 2010, 04:58 AM
  5. Ratios
    Posted in the Algebra Forum
    Replies: 3
    Last Post: February 9th 2010, 05:09 AM

Search Tags


/mathhelpforum @mathhelpforum