A research doctor wanted to estimate the average total cholesterol level of general adult population. He took a random sample of 12 adults for blood test and obtained the following sample. Assume that total cholesterol level of adult population is normally distributed.
Use these data to create a 95% confidence interval for the population mean total cholesterol level.
175, 234, 189, 256, 170, 187, 192, 225, 245, 251, 195, 230
a) Find the sample mean and the standard deviation (round to two decimal places)
b) 95% confidence interval for the population mean total cholesterol level (round to two decimal places)