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Math Help - Normal probability calculations

  1. #1
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    Exclamation Normal probability calculations

    Let X~N(0,1) . Compute each in terms of function ϕ. (0 being mu and 1 being delta^2)
    And evaluate it numerically.

    1. P(X<=-5)
    2. P(-2<=X<=7)
    3. P(X>=3)

    for the first one i get
    ϕ(-5)

    But how do i evaluate it?

    this is a wiki page on it
    Normal distribution - Wikipedia, the free encyclopedia
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  2. #2
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    #1 is correct.

    #2 \phi (7) - \phi ( - 2)

    #3 Is for you to do.
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  3. #3
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    but dont i need to get numerical values, since the question says "And evaluate it numerically"...?

    and for c would it be

    ϕ(inf)-ϕ(3)
    or just
    1-ϕ(3)
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  4. #4
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    Quote Originally Posted by Sneaky View Post
    but dont i need to get numerical values, since the question says "And evaluate it numerically"...?
    Sorry, I don't do numbers.
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  5. #5
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    ok, is c
    ϕ(inf)-ϕ(3) ?
    i dont understand what ϕ(inf) means?
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  6. #6
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    For the second:
    2. P(-2<=X<=7)=P(-2<=Z<=7)=P(Z<=7)-P(Z<=-2)=P(Z<=7)-P(Z>2)=P(Z<=7)-(1-P(Z<=2))
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  7. #7
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    Quote Originally Posted by Sneaky View Post
    ok, is c
    ϕ(inf)-ϕ(3) ?
    i dont understand what ϕ(inf) means?
    \displaystyle\lim _{x \to \infty } \phi (x) = 1.
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