Mac and Charlie are claiming that their diet will help people lose weight within a month. In order to estimate the mean weight loss of all customers

Mac and Charlie are claiming that their diet will help people lose weight within a month. In order to estimate the mean weight loss of all customers they take a sample of 18 dieters and record their weight loss one month after going the program. The sample mean is 12.5 pounds and the standard deviation is 9.2 pounds please compute the 95% confidence interval for the population mean.