A Quality Analyst wants to construct a control chart for determining whether three machines,all producing the same product,are under control with regard to a particular quality variable.Accordingly,he sampled four units of output from each machine,with the following results: What is the estimate of the process mean based on this limited number of samples?
A)16
B)19
C)20
D)21
E)23

Question

A Quality Analyst wants to construct a control chart for determining whether three machines,all producing the same product,are under control with regard to a particular quality variable.Accordingly,he sampled four units of output from each machine,with the following results:  What is the estimate of the process mean based on this limited number of samples?
A)16 
B)19 
C)20 
D)21 
E)23

Quizplus · Accepted Answer

To estimate the process mean, we need to calculate the average of all the samples.

Machine 1: (10+12+14+16)/4 = 13 
Machine 2: (18+20+22+24)/4 = 21 
Machine 3: (20+22+24+26)/4 = 23

Now, to get the estimate of the process mean, we need to take the average of the sample means, which is 
(13 + 21 + 23)/3 = 19

Therefore, the estimate of the process mean is 19. The best choice is (B) only.

A Quality Analyst Wants to Construct a Control Chart for Determining