A study is run to determine the mean total cholesterol level in children 2-6 years of age. A sample of 9 participants is chosen and their total cholesterol levels are measured as follows.
185 225 240 196 175 180 194 147 223
a) Suppose the mean total cholesterol level is 190 in children 2-6 years of age at the national level. Test whether the cholesterol level in this sample is important different from national level?
b) Make a 95% confidence interval for the true mean total cholesterol levels in children 2-6 years of age.