
Answer:
The proportion follows normal distribution,
 Mean u = 0.39
 standard deviation σ = 0.0218
Step-by-step explanation:
Solution:-
- Lets assume the population proportion ( p ) to be the percentage of adult Americans who believe that marriage is now obsolete.
- We will check for normality:
 Lets take,  p^ = p  (Mean proportion of the distribution)
- The condition of normality,
         n*p*( 1 - p ) ≥ 10
Where, n : The sample size taken.
         500*0.39*( 1 - 0.39 ) = 500*0.39*( 0.61 )
         118.95 ≥ 10
- Hence, with the testing statistics the condition for normality are validated. Hence, the distribution for proportion of adult americans who believe that marriage is now obsolete follows a normal distribution.
- The parameters of the distribution are:
  Mean : u = p^ = p = 0.39
  Standard deviation σ =  [tex]\sqrt{\frac{p*(1-p)}{n} }[/tex] =   [tex]\sqrt{\frac{0.39*(1-0.39)}{500} } = \sqrt{\frac{0.39*(0.61)}{500} } =0.0218[/tex] Â
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