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Math Help - Probability

  1. #1
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    Probability

    Probability

    Sandra's music bag contains:
    3 cds of country music
    6 cds of rock and roll
    4 cds of rap music
    5 cassette tapes of country music
    1 cassette tape of rock and roll
    3 cassette tapes of rap music

    a) As Sandra drives, she often reaches into her bag and randomly pulls out some music. What is the probably that she will select some rap music?

    b) Find P(CD), that is, the probability that she will randomly select a CD (of any type of music).

    c) Find the probability that she will select a cassete of country music.

    d) Find the probability that the music she randomly selects is not rock and roll.

    Please help I don't know how to find probability because Im not sure but I think theres a special way to do it. 'thanks.
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  2. #2
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    A: Find the total of rap music over the total of music so it would be \frac{7}{22}

    B: Find the total cds over total music: \frac{13}{22}

    C: Cassette of country music over entire collection \frac{5}{22}

    D: Total of music that is not rock and roll over total \frac{15}{22}
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  3. #3
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    Lightbulb

    A]

    B]

    C]

    D]
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  4. #4
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    Hello, peachgal!

    Edit: Made an awful blunder in my chart . . . *blush*
    . . . I'll correct it now . . .

    Sandra's music bag contains:
    3 CDs of country music
    6 CDs of rock and roll
    4 CDs of rap music
    5 tapes of country music
    1 tape of rock and roll
    3 tapes of rap music

    As Sandra drives, she often reaches into her bag and randomly pulls out some music.
    We can organize the information . . .

    \begin{array}{cccccccc}<br />
& | & \text{CD} & | & \text{Tapes} & | &  \text{Total} & | \\ \hline<br />
\text{C \& W} & | &  3 & | &  5 & | & 8 & | \\<br />
\text{R \& R} & | & 6 & | & 1 & | & 7 & | \\<br />
\text{Rap} & | & 4 & | & 3 & | & 7 & | \\ \hline<br />
\text{Total} & | & 13 & | & 9 & \ & 22 & |\end{array}


    What is the probably that she will select some rap music?
    There are 22 units, 7 are Rap music. . P(\text{Rap}) \:=\:\frac{7}{22}


    b) Find P(CD), the probability that she will randomly select a CD.
    There are 22 units, 13 are CDs. . P(\text{CD}) \:=\:\frac{13}{22}


    c) Find the probability that she will select a tape of country music.
    There are 22 units, 5 are C&W tapes: . P(\text{C\&W tape}) \:=\:\frac{5}{22}


    d) Find the probability that the music she randomly selects is not rock and roll.
    There are 22 units, 15 are not R & R: . P(\text{not R\&R}) \:=\:\frac{15}{22}

    Last edited by Soroban; October 28th 2007 at 10:19 AM.
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  5. #5
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    Soroban watch your numbers...There are 6 cds of Rock and Roll
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  6. #6
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    the total is 22 not 19 cuz the cds of the R & R is 6 not 3
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