TABLE 17-8
Recently, a University Switched to a New Type

Short Answer

TABLE 17-8
Recently, a university switched to a new type of computer-based registration. The registrar is concerned with the amount of time students are spending on the computer registering under the new system. She decides to randomly select 8 students on each of the 12 days of the registration and determine the time each spends on the computer registering. The range, mean, and standard deviation of the times required to register are in the table that follows.
$\begin{array}{rrrr} \underline {\text { Day }}& \underline {\text { Range }}& \underline {\text { Mean }}& \underline {\text { Std.Dev. }}\\ 1 & 10 & 5.250 & 3.4949 \\2 & 31 & 15.250 & 10.3060 \\3 & 13 & 20.375 & 4.9262 \\4 & 21 & 22.875 & 8.3911 \\5 & 35 & 8.500 & 11.3767 \\6 & 18 & 7.875 & 6.9372 \\7 & 25 & 11.250 & 8.5815 \\8 & 30 & 7.875 & 9.5235 \\9 & 17 & 10.250 & 6.3640 \\10 & 22 & 9.500 & 7.8740 \\11 & 27 & 7.875 & 8.7086 \\12 & 26 & 12.875 & 9.3723\end{array}$
-Referring to Table 17-8, an $\bar { X }$ chart is to be used for the time required to register. One way to obtain the control limits is to take the grand mean and add and subtract the product of A₂ times the mean of the sample ranges. For this data set, the value of A₂ is ________.