A Quality Analyst wants to construct a control chart for determining whether three machines, producing the regard to particular quality variable. Accordinglyhe analyzed four units of output $($ OBSERVATIONS$)$ from each results: Machine # $18$ Measurements $161616251825262525$ # $2$ #$324$ What is the average dispersion range $($ R bar$)$ based upon the data? Multiple Choice $23235\mathrm{.}421$ Ne Prev $17$ of $28$