QUESTION $9$

Samples of $n=6$ items each are taken from a process at regular intervals. A quality characteristic is measured and $\stackrel{}{x}$ and $R$ values are calculated for each sample. Assume that the quality characteristic is normally distributed. After $50$ samples, we have:

${\displaystyle \underset{i=1}{\overset{50}{}}}{\stackrel{}{x}}_i=2100$ and ${\displaystyle \underset{i=1}{\overset{50}{}}}{R}_i=200$

If the specification limits are $41+-5\mathrm{.}0.$ Assuming that items exceeding the upper specification limit it can be reworked. What percentage of rework is the process producing?