$6\mathrm{.}5)$ The peak friction angles, ${}_p^{\text{'}},$ measured in a sand layer

$2m(6ft)$ below the surface in $10$ tests are given below:

Calculate the mean, standard deviation, and coefficient of

variation of ${}_p^{\text{'}}.$ What value of ${}_p^{\text{'}}$ would you use in a design

of a foundation? What concerns, if any, do you have about

the data with regard to the ${}_p^{\text{'}}$ selected for the design? What

range of values will you consider for design?