Five data entry operators work at the data processing department of the Royal Bank. Each day for $30$ days, the number of defective records in a sample of $350$ records typed by these operators has

been noted, as follows:

a$)$ Establish $3$ upper and lower control limits$.$

$UC{L}_p=,($enter your response as a fraction between $0$ and $1,$ rounded to three decimal places$).$