Question

A new industrial oven has just been installed at Piatt Bakery. To develop experience regarding the oven temperature, an inspector reads the temperature at four different places inside the oven each half hour starting at 8:00 a.m. The last reading was at 10:30 a.m., for a total of six samples. The first reading, taken at 8:00 a.m., was 351 degrees Fahrenheit. (Only the last two digits are given in the following table to make the computations easier.)

	Reading 1	Reading 2	Reading 3	Reading 4
TIMES	1	2	3	4
8:00 am	51	58	44	49
8:30 am	50	47	49	53
9:00 am	51	55	44	49
9:30 am	53	48	33	64
10:00 am	50	50	57	51
10:30 am	55	48	49	47

A) File On the basis of this initial experience, determine the control limits for the range. (Round your intermediate calculations and final answers to 2 decimal places.)

LCL =

UCL =

B) For each time period, is the temperature out of control?

Answer 1

Reading 1	Reading 2	Reading 3	Reading 4
TIMES	1	2	3	4	xbar	Rbar
8:00 AM	51	58	44	49	50.5	14
8:30 AM	50	47	49	53	49.75	6
9:00 AM	51	55	44	49	49.75	11
9:30 AM	53	48	33	64	49.5	31
10:00 AM	50	50	57	51	52	7
10:30 AM	55	48	49	47	49.75	8
				average	50.208	12.833

A)

for sample size n=4, criitcal value of constant D4=

2.282

lower control limit (LCL)=D3R̅ =

0.00

upper control limit (UCL) =D4R̅ =

29.29

b)

for 9:30 AM range falls outside of control limits, therefore  temperature is out of control