Question

A bolt manufacturer wants to investigate the machine that produces bolts with a diameter of 0.23 centimeters. If the variance of the diameters is equal to 0.025. then the machine is working as expected. A random sample of 26 bolts has a standard deviation of 0.2318. Does the manufacturer have evidence at the α=0.1 level that the variance of the bolt diameters is more than required? Assume the population is normally distributed

Step 1 of 5: State the null and alternative hypotheses. Round to four decimal places when necessary.

Step 2 of 5: Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places.

Step 3 of 5: Determine the value of the test statistic. Round your answer to three decimal places.

Step 4 of 5: Make the decision

Step 5 of 5: What is the conclusion?

Answer 1

step 1:

Null hypothesis: Ho:       σ2	=	0.025
Alternate hypothesis: Ha:        σ2	>	0.025

Step 2 of 5:

for 10 % level and given df critical values of X2 =

21.064

Step 3 of 5:

test statistic χ2=(n-1)s2/σ2=

53.731

Step 4 of 5: since test statistic is higher than critical value , we reject null hypothesis

Step 5 of 5: we can conclude that the variance of the bolt diameters is more than required