Question: Anthropology: Navajo Reservation

What was the age distribution of prehistoric Native Americans? Extensive anthropologic studies in the southwestern United States gave the following information about a prehistoric extended family group of 80 members on what is now the Navajo Reservation northwestern New Mexico.

Estimate the mean age expressed in years for this community, the sample variance, and the sample standard deviation. For the class 31 and over, use 35.5as the class midpoint.