Question: We wish to estimate the mean serum indirect bilirubin level of 4-day-old infants. The mean for a sample of 160 infants was found to be 5.98 mg/100 cc. Assume that bilirubin levels in 4-day-old infants are approximately normally distributed with a standard deviation of 3.5 mg/100 cc. Construct a 95% confidence interval for the true mean bilirubin level in 4-day-old infants.