n order to compute the control$$ limits$,$ identify the value of z$.$ We want a type I error of $1$ percent, or $0\mathrm{.}5$ percent of the curve above the UCL and $0\mathrm{.}5$ percent below the LCL$.$ Consequently, we need to find the$$ z$-$value in the standard normal distribution table that leaves only $0\mathrm{.}5$ percent in the upper portion of the normal curve.