A theatrechain whats to estimate the average number of party rooms rented daily each month.The standard deviation is unknown.What is the 95% confidence interval?

Which type of confidence interval is necessary to use in this case?

a) confidence interval estimate for the difference between two means (t-statistic)

b) confidence interval estimate of a variance (chi-squared statistic)

c) confidence interval estimate of a mean (t-statistic)

Thank you