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Arithmetic Probability

This topic has 6 member replies
dheaven1 Junior | Next Rank: 30 Posts Default Avatar
Joined
08 Feb 2010
Posted:
10 messages

Arithmetic Probability

Post Thu Feb 18, 2010 11:18 pm
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.

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    thephoenix Legendary Member
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    Post Thu Feb 18, 2010 11:46 pm
    dheaven1 wrote:
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.
    imO b

    IF U USE DOUBLE MATRIX SYS OF mgmat

    U WILL GET THE NO OF PEPOLE WHO INVEST IN BOND AND NOT OIL STOCK=28*25

    PROB=28*25/2500=7/25

    ajith Legendary Member
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    Post Thu Feb 18, 2010 11:49 pm
    dheaven1 wrote:
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.
    35 percent invests in municipal bonds this includes the 7% who invested in both municipal bonds and oil stocks.

    So 28 percent invests in municipal bonds but not in oil stocks

    Now the probability is 28/100 = 7/25

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    harsh.champ Legendary Member
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    Post Fri Feb 19, 2010 12:07 am
    dheaven1 wrote:
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.
    Hey dheaven1,
    If you are having problems with such type of questions,you should try doing them using Venn-Diagrams.
    It will seem very easy when you have the diagram by your side.
    In probability,I have found Venn-Diagram to be very useful for advanced problems.
    Also,You should consult set theory side by side.


    As for the question it can be solved using the equation:-
    P(A U B) = P(A) + P(B) - P(A n B) [U-union, n -intersection]

    In the question,we have to find P(B) - P(A n B)

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    shashank.ism Legendary Member
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    Post Sun Feb 21, 2010 3:34 pm
    dheaven1 wrote:
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.
    %ge \invested in mutual bond = 35 m

    person who invetsed in mutual bond = 35 %
    person who invested in oil stocks = 18%
    person who invested in bopt h = 7%
    person who invested in mutual bond and not oil stocks= 35 -7 = 28

    so %ge = 28 /100 = 7 /25 Ans B

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    garavkaram Newbie | Next Rank: 10 Posts
    Joined
    16 Nov 2010
    Posted:
    1 messages
    Post Tue Nov 16, 2010 6:42 am
    Hi Experts, help me pls.

    here's what I am stuck at:-

    1.) person who invested in oil stocks = 18%
    1.a) person who NOT invested in oil stocks = (100-18) = 82%
    2.) person who invetsed in municipal bond = 35 %

    combining 1.a. & 2 we get,
    person invested in municipal bond AND NOT in oil stock = 82% * 35 % which is not 7/25.

    I am sure I am missing something but dont know what..

    Would appreciate your support.

    regards,

    Fractal Master | Next Rank: 500 Posts Default Avatar
    Joined
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    Post Sun Jul 31, 2011 9:17 am
    ajith wrote:
    dheaven1 wrote:
    Among a group of 2,500 people, 35 percent invest in
    municipal bonds, 18 percent invest in oil stocks, and
    7 percent invest in both municipal bonds and oil
    stocks. If 1 person is to be randomly selected from
    the 2,500 people, what is the probability that the
    person selected will be one who invests in municipal
    bonds but NOT in oil stocks?

    A. 9/50
    B. 7/25
    C. 7/20
    D. 21/50
    E. 27/50


    I need explanation on why you would factor in the 7 percent invested in both municipal bonds and oil stocks.
    35 percent invests in municipal bonds this includes the 7% who invested in both municipal bonds and oil stocks.

    So 28 percent invests in municipal bonds but not in oil stocks

    Now the probability is 28/100 = 7/25
    wow, what an easy way! it takes like 15 seconds to solve the question like this! i didn't recognize that unfortunately and hence draw a double-matrix, which costs me some seconds...

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