A Quality Analyst Wants to Construct a Sample Mean Chart $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\text { Weight }$

question 94

Essay

A quality analyst wants to construct a sample mean chart for controlling a packaging process. He knows from past experience that the process standard deviation is two ounces. Each day last week, he randomly selected four packages and weighed each. The data from that activity appears below.
$\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\text { Weight }$
$\begin{array}{|l|l|l|l|l|}\hline \text { Day } & \text { Package 1 } & \text { Package 2 } & \text { Package 3 } & \text { Package 4 } \\\hline \text { Monday } & 23 & 22 & 23 & 24 \\\hline \text { Tuesday } & 23 & 21 & 19 & 21 \\\hline \text { Wednesday } & 20 & 19 & 20 & 21 \\\hline \text { Thursday } & 18 & 19 & 20 & 19 \\\hline \text { Friday } & 18 & 20 & 22 & 20\\\hline\end{array}$
(a) Calculate all sample means and the mean of all sample means.
(b) Calculate upper and lower control limits that allow for natural variations.
(c) Is this process in control?

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Definitions:

Post-Closing Trial Balance

A list of all accounts and their balances after closing entries are made, showing only balance sheet accounts.

Temporary Accounts

Accounts that are closed at the end of each accounting period. These include revenue, expense, and dividend accounts.

Permanent Accounts

Accounts that carry their ending balances over to the next accounting period and are not closed out.

Adjusting Entries

Journal entries made at the end of an accounting period to allocate income and expenditure to the period in which they actually occurred.