Question

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 79 members on what is now a Native American reservation. For this community, estimate the mean age expressed in years, the sample variance, 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.) Age range (years) 1-10 11-20 21-30 31 and over Number of individuals 35 17 19 8

Age range (years)	1-10	11-20	21-30	31 and over
Number of individuals	35	17	19	8

mean =

s^2 =

s =

Answer 1

The table given by ,

Age range	Class boundaries	Mid points[xi]	No. of individuals[fi]	fi xi	fi xi2
1-10	0.5 - 10.5	5.5	35	192.5	1058.75
11-20	10.5-20.5	15.5	17	263.5	4084.25
21-30	20.5-30.5	25.5	19	484.5	12354.75
31 and over	30.5 and over	35.5	8	284	10082
Total			79	1224.5	27579.75

From table ,

= 1224.5 / 79 = 15.5

= (27579.75/79) - 15.5²

^{= 349.11 - 240.25}

^=108.86

^{~ 108.9}

^=10.4