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:
Machine Measurements
Number1 17 15 15 17
Number2 16 25 18 25
Number3 23 24 23 22
What is the estimate of the process mean for whenever it is under control?
a. 16
b. 19
c. 20
d. 21
e. 23

Answer 1

Answer:

c. 20

Explanation:

The summary of the given information shows that a Quality Analyst sampled four units of output from each machine, with the following results:

Machine Measurements

Number 1        17 15 15 17

Number 2       16 25 18 25

Number 3       23 24 23 22

In order to determine the estimate of the process mean for whenever it is under control, we need to find the mean of each Machine and find the average of the three machines together

i.e

For Machine Number 1 ;

Mean = (17+15+15+17)/4

Mean = 64/4

Mean = 16

For Machine Number 2 ;

Mean = (16+25+18+25)/4

Mean = 84/4

Mean = 21

For Machine Number 3;

Mean = ( 23+24+23+22)/4

Mean = 92/4

Mean = 23

∴

The estimate of the process mean for whenever it is under control

= (16 + 21 + 23)/3

The estimate of the process mean for whenever it is under control = 60/3

The estimate of the process mean for whenever it is under control = 20