Please include workings out

b} The age of adults in Bull-a-stan was estimated by considering a sample with sample mean equal to 30, standard deviation equal to 10, and sample size equal to 40. Calculate the 99% confidence interval estimate of the true mean of age of adults in Bull-a- stan. If the sample size was 18, show and comment on how the method of calculation and condence interval were altered. (13 marks)