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It is estimated that 53% of adults in the Lebanese population have never smoked.?

. If a sample of 110 Lebanese adults is randomly selected,

(a) What is the probability that the sample proportion will be less than 0.50.

(b) Now suppose we are willing to estimate the population proportion . From the sample of 110 Lebanese adult 60 have never smoked. Find the 99% confident interval of the population proportion.

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2 Answers

Relevance
  • 7 years ago
    Favorite Answer

    Use the formula

    P(X) = 8a +8b +99999c +08637421d

    then go to your school, and ask your teacher

  • cidyah
    Lv 7
    7 years ago

    a) Proportion of non-smokers = 0.53

    Mean of sample proportion = 0.53

    Standard deviation of sample proportion = sqrt [ p(1-p)/n] = sqrt [ (0.53)(0.47) / 110] = 0.0476

    P( p^ < 0.50) is required :

    μ = 0.53

    σ = 0.0476

    standardize x to z = (x - μ) / σ

    P(x < 0.5) = P( z < (0.5-0.53) / 0.0476)

    = P(z < -0.6303) = 0.2643

    (From Normal probability table)

    b)

    The z-value for 99% confidence interval is 2.575

    Sample proportion phat = 0.6

    Variance of proportion = p*(1-p)/n

    = 0.6(0.4)/110 =0.0021818

    S.D. of p is sqrt[0.002182] = 0.0467

    Confidence interval:

    phat-zval*sd = 0.6 - (2.575)(0.04671)

    phat-zval*sd = 0.6 + (2.575)(0.04671)

    99% confidence interval is ( 0.48 , 0.72 )

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