The City Square Grocery and Meat Market has a large meat locker in which a constant temperature of approximately 40 F should be maintained. The market manager has decided to construct an R-chart to monitor the temperature inside the locker. The manager had one of the market employees take sample temperature readings randomly five times each day for 20 days in order to gather data for the control data. The third set of data in the following file are the temperature sample observations: Quality Homework Control Chart Raw Data. xls

a. Construct an x-bar chart and R-chart based on these data using 3-sigma limits.

b. Does it appear that the temperature is in control according to the criteria established by management?

Temperatures
Sample 1 2 3 4 5 Average Range
1 46.3 48.1 42.5 43.1 39.6
2 41.2 40.5 37.8 36.5 42.3
3 40.1 41.3 34.5 33.2 36.7
4 42.3 44.1 39.5 37.7 38.6
5 35.2 38.1 40.5 39.1 42.3
6 40.6 41.7 38.6 43.5 44.6
7 33.2 38.6 41.5 40.7 43.1
8 41.8 40 41.6 40.7 39.3
9 42.4 41.6 40.8 40.9 42.3
10 44.7 36.5 37.3 35.3 41.1
11 42.6 43.5 35.4 36.1 38.2
12 40.5 40.4 39.1 37.2 41.6
13 45.3 42 43.1 44.7 39.5
14 36.4 37.5 36.2 38.9 40.1
15 40.5 34.3 36.2 35.1 36.8
16 39.5 38.2 37.6 34.1 38.7
17 37.6 40.6 40.3 39.7 41.2
18 41 34.3 39.1 45.2 43.7
19 40.9 42.3 37.6 35.4 34.8
20 37.6 39.2 39.3 41.2 37.6