Answer:
A sample of is needed, in which E is the desired margin of error, as a proportion. If we find a decimal value, we round up to the next whole number.
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 of:
In a previous study of 1012 randomly chosen respondents, 374 said that there should be such a law.
This means that
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
How large a sample size is needed to be 95% confident with a margin of error of E?
A sample size of n is needed, and n is found when M = E.
A sample of is needed, in which E is the desired margin of error, as a proportion. If we find a decimal value, we round up to the next whole number.
