An Anthropologist Is Studying the Strength of Fragments of Pottery

An anthropologist is studying the strength of fragments of pottery ("sherds") found in
three archeological sites in the Phoenix Basin area of Arizona. Her study involves
applying force to the sherds until they break, so she plans to use only a small sample
of available artifacts. Her data contains the location of the sherd (site), and the
weight and thickness of the sherd. A partial list of the data is shown below. $\begin{array}{|l|l|l|l|}\hline \text { Sherd \# } & \text { Site } & \text { Weight }(\mathrm{g}) & \text { Thick }(\mathrm{mm}) \\\hline 1 & \text { Sacaton } & 14.7 & 5.41 \\2 & \text { Sacaton } & 14.6 & 5.75 \\3 & \text { Gila Plain } & 17.9 & 7.09 \\4 & \text { Sacaton } & 14.7 & 6.14 \\5 & \text { Gila Plain } & 13.1 & 5.11\\6 & \text { Casa Grande } & 18.5 & 6.51 \\7 & \text { Casa Grande } & 13.4 & 5.92 \\\ldots & \ldots & \ldots & \ldots \\1000 & \text { Gila Plain } & 14.6 & 4.01 \\\hline\end{array}$ a) Briefly describe a process to select a simple random sample of size n = 20 from
this list of sherds. You may assume that you have a random number table to work
with, but do NOT carry out the process you describe.
b) Briefly describe how a stratified random sample could be selected with strata
corresponding to archeological sites.