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Thread: Help me with Math

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    Help me with Math

    A study published in a consumer magazine indicated that when a husband and a wife shop for a car, the husband exerts the primary influence in the descision 70% of the time. Five couples who will be purchasing a car are selected at random. Determine the probability of:

    a) In exactly two of the couples, the husband will exert the primary influence on the decision.

    b) In all five couples, the husband will exert the primary influence on the decision.

    I got for a).132 and for b).168 ...is this correct? I dont have an answer key to check.

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    Headless Kristin's Avatar
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    I got something different for a?

    a) 0.7 x 0.7 x 0.3 x 0.3 x 0.3 = 0.01323

    b is correct, though.

    b) 0.7^5 = 0.16807

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    Zachafer (05-25-2012)

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    bamag's Avatar
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    Quote Originally Posted by Prince View Post
    I got something different for a?

    a) 0.7 x 0.7 x 0.3 x 0.3 x 0.3 = 0.01323

    b is correct, though.

    b) 0.7^5 = 0.16807
    Both are correct. For a), you get the answer by using binomial probability density function. (5C2) * (.7^2) * (.3^3) = .132

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    Prince (05-26-2012)

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    Quote Originally Posted by bamag View Post
    Both are correct. For a), you get the answer by using binomial probability density function. (5C2) * (.7^2) * (.3^3) = .132
    Ah, of course. Because it doesn't state which two couples.

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