A large chain of movie theaters wants to estimate the average number of unoccupied seats per show. To accomplish this, thie tickets sales records of 64 shows were randomly selected and the number of unoccupied seats was calculated. The sample data showed that the mean number of unoccupied seats was 20 with a standard deviation of 10.
Estimate the population mean number of unoccupied seats per show, using 99% confidence interval.