Answer:
a) We need a sample size of at least 2401.
b) We need a sample size of at least 1936.
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:
95% confidence level
So , z is the value of Z that has a pvalue of , so .
(a) you are unwilling to predict the proportion value at your school and
We use , which is when we are going to need the largest sample size.
So we need to find We need a sample size of at least 2401.
(b) you use the results from the surveyed school as a guideline.
Now the same calculation, just with . So
We need a sample size of at least 1936.
