Answer:
The 95% confidence interval would be given (0.622;0.644).
We are confident (95%) that the true proportion of people that said that they change their nail polish once a week is between 0.622 and 0.644
Step-by-step explanation:
Data given and notation
n=7000 represent the random sample taken
X=4431 represent the people that said that they change their nail polish once a week
estimated proportion of people that said that they change their nail polish once a week
represent the significance level
Confidence =0.95 or 95%
p= population proportion of people that said that they change their nail polish once a week
Solution to the problem
The confidence interval would be given by this formula
For the 95% confidence interval the value of and
, with that value we can find the quantile required for the interval in the normal standard distribution.
And replacing into the confidence interval formula we got:
And the 95% confidence interval would be given (0.622;0.644).
We are confident (95%) that the true proportion of people that said that they change their nail polish once a week is between 0.622 and 0.644