9. A researcher interested in the age at which women have their first child surveyed a simple random sample of 250 women who have one child and found an approximately normal distribution with a mean age of 28 and a standard deviation of 4.5. According to the Empirical rule, approximately 68% of women had their first child between the ages of a. 14.5 years and 41.5 years b. 19.0 years and 37.0 years c. 23.5 years and 32.5 years d. 25.8 years and 30.3 years