A doctor is interested in people who have experienced an unexplained episode of vitamin D intoxication. She took a SRS of size 12 from the people who have experienced an unexplained episode of vitamin D intoxication and measured the calcium level in mmol/l in each individual. The sample mean is x = 2.87 mmol/l. Assume that the distribution of the calcium level of people with an unexplained episode of vitamin D intoxication is normally distributed with standard deviation of σ = 0.40.(a) Calculate a 99% confidence interval for μ = the true mean calcium level of the population of people who experienced an unexplained episode of vitamin D intoxication.