In: Statistics and Probability
13. A textile fiber manufacturer is investigating a new drapery yarn, which the company
claims have a mean thread elongation of 24 kilograms with a standard deviation of 0.5
kilograms. The company wishes to test the hypothesis
using a random sample of 4 specimens.
H0: μ =24 against H1: μ<24
(a) What is the type I error probability if the critical region is defined as kilograms?
(b) Find beta for the case where the true mean elongation is 23.24 kilograms.
(c) Find beta for the case where the true mean is 23.5 kilograms.
Answer:
Given that:
A textile fiber manufacture is inversting a new drepery yarn,which the company claims has a mean thread elongation of 24 kilograms with a standard deviation of 0.5.
a)
The required probabillity is
The distribution of the sample mean is approximately normal with the mean and the standard deviation
The z-value that corresponds to the critical value 23.5 is
Therefore,
b) We find as
The distribution of the sample mean is approximately normal with the mean and the standard deviation
The z-value that corresponds to the critical value 23.5 is
Therefore,
c)
We find as
The distribution of the sample mean is approximately normal with the mean and the standard deviation
The z-value that corresponds to the critical value 23.5 is
Therefore,