I am confused on how to do x and s^2. Explain this to me please.

What was the age distribution of prehistoric Native Americans? Extensive anthropological studies in the southwestern United States gave the following information about a prehistoric extended family group of 3'4 members on what Is now a Native American reservation. For this community, estimate the mean age expressed in years, the sample varianoe, and the sample standard deviation. For the class 31 and over, use 35.5 as the class midpoint. (Round your answers to one decimal place.) we ran-e ars 1-10 11-20 21-30 31 and over 32 16 19 ? ;=x sz=x .-_., Submit Answer Save Progress Preoiioe Ano'lher Version