According to creditcard.com, 29% of adults do
not own a credit card.
(a) Suppose a random sample of 500 adults is asked, “Do you own a credit card?” Describe the sampling distribution of p-hat, the proportion of adults who own a credit card.
(b) What is the probability that in a random sample of 500 adults more than 30% do not own a credit card?

Question

According to creditcard.com, 29% of adults do
not own a credit card.
(a) Suppose a random sample of 500 adults is asked, “Do you own a credit card?” Describe the sampling distribution of p-hat, the proportion of adults who own a credit card.
(b) What is the probability that in a random sample of 500 adults more than 30% do not own a credit card?

perl · Answer

this is a binomial distribution
the mean is n*p , 
the st. dev is sqrt( n*p*(1-p))

anonymous · Answer

I thought I have to use the formulas for sampling distributions?

anonymous · Answer

I tried b and I got:
p(p>30) = 1-0.6879=0.3121
Did I do it correctly?

perl · Answer

oh nevermind, you are right