5) How does the 99% confidence interval compare to the 90% interval? (Refer to 12.4 Level of Confidence page 226-227) 2. For a population of infants subjected to fetal surgery for congenital anomalies, the distribution of gestational ages at birth is approximately normal with unknown mean and standard deviation of 3.5 weeks. 1) A random sample of 16 such infants have mean gestational age of 29.8 weeks. Construct a 95% confidence interval for the true population mean. 2) How large a sample would be required for the 95% confidence interval to have length of 3 weeks? (upper bound - lower bound -3) 3) how large a sample would be needed for the 95% confidence interval to have length of 2 weeks? (upper bound - lower bound =2)