Problem

Refer 10 the freezer problem 17.51 with µ= 23 and σ= 2. Temperature measurements are recor...

Refer 10 the freezer problem 17.51 with µ= 23 and σ= 2. Temperature measurements are recorded four times a day (at midnight, 0600, 1200, and 1800). Twenty samples of four observations are shown below. (a) Construct upper and lower control limits for the chart, using the given process parameter. (b) Plot the data on the control chart. (c) Is this process in control? Explain your reasoning.

Sample	Midnight	At 0600	At 1200	At 1800	Mean
1	25	26	23	23	24.25
2	22	23	29	22	23.75
3	20	24	25	21	22.50
4	21	25	22	2i	22.75
5	21	23	21	23	22.00
6	26	25	27	26	26.00
7	21	23	25	20	22.25
8	25	23	22	25	23.75
9	22	24	24	22	23.00
10	27	23	26	25	25.25
11	24	23	20	21	22.00
12	25	21	23	20	22.25
13	26	26	21	21	22.75
14	26	22	26	22	24.00
15	21	24	20	19	21.00
16	23	26	23	23	23.75
17	23	21	24	21	22.25
18	25	22	22	23	23.00
19	24	20	21	22	21.75
20	24	21	23	21	22.25