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Math Help - basic probability

  1. #1
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    Question basic probability

    The probability that a retired man will live 10 more yrs. is .60
    The probability that a retired woman will live 10 more is .70

    What is the prob. that both will be alive in 10 years?

    What is the prob. that he will be alive but she won't?

    What is the prob. that in 10 yrs. at least 1 will be alive?

    help - please
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  2. #2
    Bar0n janvdl's Avatar
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    Quote Originally Posted by numnuts View Post
    The probability that a retired man will live 10 more yrs. is .60
    The probability that a retired woman will live 10 more is .70

    What is the prob. that both will be alive in 10 years?

    What is the prob. that he will be alive but she won't?

    What is the prob. that in 10 yrs. at least 1 will be alive?

    help - please
    Look at the addition rule for sets.

    a) P(M \cap W) =

    b) P(M \cap W^{c}) =

    c) P(M \cap W^{c}) + P(M^{c} \cap W) =
    (Man alive and woman dead OR man dead and woman alive.)
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  3. #3
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    Quote Originally Posted by janvdl View Post
    Look at the addition rule for sets.

    a) P(M \cap W) =

    b) P(M \cap W^{c}) =

    c) P(M \cap W^{c}) + P(M^{c} \cap W) =
    (Man alive and woman dead OR man dead and woman alive.)
    Another hint is to assume that M and W are independent events.
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  4. #4
    Bar0n janvdl's Avatar
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    Quote Originally Posted by mr fantastic View Post
    Another hint is to assume that M and W are independent events.
    On a side-note:
    I am so out of practice with my set theory
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  5. #5
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    Thank you - how about this one

    a medicine is 80% effective - it is tested on 14 people

    What is the prob. that all 14 helped?

    What is the prob. that fewer than 9 of 14 will be helped?

    What is the prob. that 12 or more will be helpled?

    Do I use the same formulas
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  6. #6
    Bar0n janvdl's Avatar
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    Quote Originally Posted by numnuts View Post
    a medicine is 80% effective - it is tested on 14 people

    What is the prob. that all 14 helped?

    What is the prob. that fewer than 9 of 14 will be helped?

    What is the prob. that 12 or more will be helpled?

    Do I use the same formulas
    No, you would rather use the Binomial distribution in my opinion.
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