In: Statistics and Probability
Inference - type 2 error
3. A soda vending machine is scheduled to ship an average of
nine (9) ounces of soda per glass, with a standard deviation of one
ounce (1) ounce. The machine manufacturer wishes to set the control
limit so that for a sample of 36 soft drinks, 5% of the sample
averages is higher than the upper control limit and 5% of the
sample averages, lower than the limit of lower control
a. In what values should the control limits be programmed?
b. What is the probability that if the population average changes
to 8.9, the change will not be detected?
C. What is the probability that if the population average changes
to 9.3, the change will not be detected?
a)
here for 5% in both tails, critical z =1.645
therefore lower control limit =9-1.645*1/√36= 8.726
upper control limit =9+1.645*1/√36= 9.274
b)
probability that if the population average changes to 8.9, the change will not be detected =0.8406
c)
probability that if the population average changes to 9.3, the change will not be detected =0.4361