SCENARIO 18-8
Recently, a University Switched to a New Type

SCENARIO 18-8
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. $$\begin{array} { r l r l } \underline { \text { Day } } & \text { Range } & \underline { \text { Mean } } & \underline { \text { Std.Dev. } } \\1 & 10 & 5.250 & 3.4949 \\2 & 31 & 15.250 & 10.3060 \\3 & 13 & 20.375 & 4.9262 \\4 & 21 & 22.875 & 8.3911 \\5 & 35 & 8.500 & 11.3767 \\6 & 18 & 7.875 & 6.9372 \\7 & 25 & 11.250 & 8.5815 \\8 & 30 & 7.875 & 9.5235 \\9 & 17 & 10.250 & 6.3640 \\10 & 22 & 9.500 & 7.8740 \\11 & 27 & 7.875 & 8.7086 \\12 & 26 & 12.875 & 9.3723\end{array}$$
-Referring to Scenario 18-8, 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 $A _ { 2 }$ is ________.

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