Answer:
We need a sample of at least 752 students.
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 of the interval is:
90% confidence level
So , z is the value of Z that has a pvalue of
, so
.
How large of a sample must she have to get a margin of error less than 0.03
We need a sample of at least n students.
n is found when M = 0.03.
We have no information about the true proportion, so we use .
Rounding up
We need a sample of at least 752 students.