Problem 1. P chart problem:

The dean assistant collected 50 student files every day and recorded number of files with errors for 6-day period.

Sample- Days	Number of files reviewed	Number of files w/ typing errors	p-values
1	50	17
2	50	9
3	50	12
4	50	15
5	50	26
6	50	11

a. Find the average proportion of errors (p-bar). Find the standard deviation (sigma_p).

Find the 3 sigma upper and lower control limits for error proportions.

Consider the chart below. Is process in control? Explain.

p-chart 3-Day work periods