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Math Help - Probability

  1. #1
    413
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    Probability

    At a certain university, 30% of the students major in math. Of the students majoring in math, 60% are males. Of all the students at the university, 70% are males.
    a) What is the probability that a student selected at random in the university is male and majors in math?

    b) What is the probability that a randomly selected student in the university is female or majors in math or both?


    I got a) as 18%, I am not sure how to do b).
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  2. #2
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    Quote Originally Posted by 413 View Post
    At a certain university, 30% of the students major in math. Of the students majoring in math, 60% are males. Of all the students at the university, 70% are males.
    a) What is the probability that a student selected at random in the university is male and majors in math?

    b) What is the probability that a randomly selected student in the university is female or majors in math or both?


    I got a) as 18%, I am not sure how to do b).
    Make it simple.
    Let, the number of students to 100.
    Then, 30 are for math.
    18 are male math.
    70 males altogether.
    So, 52 are males not in math.
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  3. #3
    413
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    so 30% are females, 30% majors in male and 12% are female and majors in math...

    therefore:
    =P(female)+P(math major)+P(female and math major)
    =30% +30 %+12%

    =72% correct?
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by 413 View Post
    so 30% are females, 30% majors in male and 12% are female and majors in math...

    therefore:
    =P(female)+P(math major)+P(female and math major)
    =30% +30 %+12%

    =72% correct?
    b) What is the probability that a randomly selected student in the university is female or majors in math or both?

    There are 30 female students and 18 math majors who are not female (as
    the female math majors have already been counted we don't count them
    again), so there are 48 students who satisfy the criteria out of 100, so the
    0probability is 48%.

    RonL
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