Answer:
The required sample size for the new study is 801.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
25% of all adults had used the Internet for such a purpose
This means that
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
What is the required sample size for the new study?
This is n for which M = 0.03. So
Rounding up:
The required sample size for the new study is 801.