Frank's assembly unit has decided to use a p$-$Chart with $2-$sigma control limits to monitor the proportion of defective copper wires produced by their production process. The operations manager randomly samples $100$

copper wires at $16$

successively selected time periods and counts the number of defective copper wires in the sample.

Table

Control Chart

Step $2$ of $8$ : What value of z should be used to construct the control chart?