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    In a class of students 1/3 are left handed and 1/8 wear a dental brace.
    A student is selected at random.

    What is the probability of that student.
    a) is left handed AND wears a brace
    b) is left handed but does not wear a brace
    c) does not wear a brace AND is not left handed


    Note: 1/3 and 1/8 DOES NOT = 1 :/

    Any ideas? for a) I did : 1/3 * 1/8 but then this does not compute the probs DONT = 1
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    (Original post by Reversed Flash)
    In a class of students 1/3 are left handed and 1/8 wear a dental brace.
    A student is selected at random.

    What is the probability of that student.
    a) is left handed AND wears a brace
    b) is left handed but does not wear a brace
    c) does not wear a brace AND is not left handed


    Note: 1/3 and 1/8 DOES NOT = 1 :/

    Any ideas? for a) I did : 1/3 * 1/8 but then this does not compute the probs DONT = 1
    a should be 1/3 * 1/8 giving 1/24..
    b should be 1/3 * 7/8.. so on so on, should be right tbh.
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    (Original post by Relentas)
    a should be 1/3 * 1/8 giving 1/24..
    b should be 1/3 * 7/8.. so on so on, should be right tbh.
    but the probabilities dont add up to 1?
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    (Original post by Reversed Flash)
    but the probabilities dont add up to 1?
    I dont understand what you mean.. 1/24 doesnt equal one? or are you talking about the sum of all answers?
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    (Original post by Relentas)
    I dont understand what you mean.. 1/24 doesnt equal one? or are you talking about the sum of all answers?
    1/3 + 1/8 = not equal to one. Surely they should?
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    (Original post by Reversed Flash)
    1/3 + 1/8 = not equal to one. Surely they should?
    nah, they dont. (idk if you do the "smile and kiss" method for adding fractions) but here's an example.
    1/3 + 1/8 = (8+3)/(8*3)
    that means 11/24 is what you get when you add them together. so yea, it doesn't equal one.
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    (Original post by Reversed Flash)
    In a class of students 1/3 are left handed and 1/8 wear a dental brace.
    A student is selected at random.

    What is the probability of that student.
    a) is left handed AND wears a brace
    b) is left handed but does not wear a brace
    c) does not wear a brace AND is not left handed


    Note: 1/3 and 1/8 DOES NOT = 1 :/

    Any ideas? for a) I did : 1/3 * 1/8 but then this does not compute the probs DONT = 1
    Most of the students are neither left handed nor do they wear a dental brace.

    1/3 of students are left handed
    2/3 are not

    1/8 of students wear a dental brace
    7/8 of students do not

    Some left handed people wear a dental brace but some do not.
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