Age at first marriage, Part I:The National Survey of Family Growth conducted by the Centers for Disease Control gathers information on family life, marriage and divorce, pregnancy, infertility, use of contraception, and men's and women's health. One of the variables collected on this survey is the age at first marriage. The histogram below shows the distribution of ages at first marriage of 5,534 randomly sampled women between 2006 and 2010. The average age at first marriage among these women is 23.44 with a standard deviation of 4.72 (NSFG, 2010). Assume that 4.72 is the population standard deviation. (please round ages to two decimal places)

a) Estimate the average age at first marriage of women using a 95% confidence interval.

(,)

show formula please