Refer $to$ Table $S6\mathrm{.}1(Table$ titled "Definition"$)$ for this problem.

Auto pistons $at$ Wemming Chung's plant $in$ Shanghai are produced $in$ a forging process, and the diameter $is$ a critical factor that must $be$ controlled. From sample sizes $of10$ pistons produced each day, the mean and the range $of$ this diameter have been $as$ follows:

$(pictured)$

$a$