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Math Help - Student Selection at random

  1. #1
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    Student Selection at random

    18 juniors,,,,,,,10 seniors,,,,,(6 seniors are Female)(12 Juniors Male).....
    Find the probability of a. A junior or a female?
    b. A senior or a female?
    c. A junior or a senior?

    I suck at STATS.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    i will do the first, try the other two, it's the same formula
    Quote Originally Posted by Hunt67 View Post
    18 juniors,,,,,,,10 seniors,,,,,(6 seniors are Female)(12 Juniors Male).....
    Find the probability of a. A junior or a female?
    there are 28 students in all.

    so we want P(J \text{ or } F)

    using our formula, we have:

    P(J \text{ or } F) = P(J) + P(F) - P(J \text{ and } F) = \frac {18}{28} + \frac {6 + 6}{28} - \frac {6}{28} = \frac 67

    b. A senior or a female?
    c. A junior or a senior?
    have at them

    I suck at STATS.
    this is probability
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  3. #3
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    Quote Originally Posted by Jhevon View Post
    i will do the first, try the other two, it's the same formulathere are 28 students in all.

    so we want P(J \text{ or } F)

    using our formula, we have:

    P(J \text{ or } F) = P(J) + P(F) - P(J \text{ and } F) = \frac {18}{28} + \frac {6 + 6}{28} - \frac {6}{28} = \frac 67

    have at them

    this is probability
    I am confulsed with C. a junior and a senior. If i apply the formula i get 0/28????
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Hunt67 View Post
    I am confulsed with C. a junior and a senior. If i apply the formula i get 0/28????
    how is that? it is a junior or a senior, so that is P(J) + P(S) - P(J and S). here, of course, P(J and S) = 0 since you can't be a junior and senior at the same time, so you are left with P(J) + P(S)
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