=+10.81 Are young women delaying marriage and marrying at a later age? This question was addressed in a report issued by the Census Bureau (Associated Press, June 8, 1991). The report stated that in 1970 (based on census results) the mean age of brides marrying for the first time was 20.8 years. In 1990 (based on a sample, because census results were not yet available), the mean was 23.9.

Suppose that the 1990 sample mean had been based on a random sample of size 100 and that the sample standard deviation was 6.4. Is there sufficient evidence to support the claim that in 1990 women were marrying later in life than in 1970? Test the relevant hypotheses using a 5 .01.

(Note: It is probably not reasonable to think that the distribution of age at first marriage is normal in shape.)