TABLE 18-5
a Manufacturer of Computer Disks Took Samples

Short Answer

TABLE 18-5
A manufacturer of computer disks took samples of 240 disks on 15 consecutive days. The number of disks with bad sectors was determined for each of these samples. The results are in the table that follows.
$$\begin{array} { l l l } \text { Day } & \text { Bad } & \% \text { Bad } \\\hline 1 & 9 & 0037500 \\2 & 7 & 0.029167 \\3 & 4 & 0.016667 \\4 & 6 & 0.025000 \\5 & 8 & 0.033333 \\6 & 3 & 0.012500 \\7 & 6 & 0.025000 \\8 & 10 & 0.041667 \\9 & 16 & 0.066667 \\10 & 24 & 0.100000 \\11 & 15 & 0.062500 \\12 & 9 & 0.037500 \\13 & 4 & 0.016667 \\14 & 8 & 0.033333 \\15 & 6 & 0.025000\end{array}$$
-Referring to Table 18-5, a p control chart is to be made for these data. The center line of the control chart is _____ .