Question

A certain process for manufacturing screws whose nominal diameter is 4.70 mm. Historically the process standard deviation is known to be 0.05mm. Measurements are taken on a sample with the intention of evaluating the process mean. The results were the following:

d. What is the probability of making a type I error? EXPLAIN

e. If the screw thickness specifications are: 4.70 + 0.10

i. What proportion of the screws are out of specification? Will this proportion affect the sample size?

4.52	1
4.66	4
4.67	5
4.68	7
4.69	14
4.70	9
4.71	6
4.72	4

Answer 1

x	f	xf
4.52	1	4.52
4.66	4	18.64
4.67	5	23.35
4.68	7	32.76
4.69	14	65.66
4.7	9	42.3
4.71	6	28.26
4.72	4	18.88
	50	234.37