5. Sometimes grouped data are the only data we can get our hands on. In other situations, it is easier first to group the data and then to estimate the mean and standard deviation. For example, we are provided the age distribution of prehistoric Native Americans? Extensive anthropologic studies in the southwestern United Sates gave the following information about a prehistoric extended family group of 80 members on what is now the Navajo Reservation in northwestern New Mexico. 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. [2 marks]

Age range (years): 1-10 ... 11-20 ... 21-30 ... 31 and over
# of individuals: 34 ..... 18 ....... 17 ......... 11


Mean =

Sample Variance =

Sample Standard deviation =

Got an answer just want to know if it matches!!! Lmk guys 20fg for help

This post was edited by Acceptance on Jan 21 2017 09:40pm

its not sosimple as u make it seem ill get back to u

Size = 34 + 18 + 17 + 11

Mean = [ 34 * (1+10)/2 + 18 * (11+20)/2 + 17 * (21+30)/2 + 11 * 35.5 ] / Size

Variance = [ 34 * (5.5 - Mean)² + 18 * (15.5 - Mean)² + 17 * (25.5 - Mean)² + 11 * (35.5 - Mean)² ] / Size

Standard deviation = Variance ^ 0.5