Question

A bolt manufacturer is very concerned about the consistency with which his machines produce bolts. The bolts should be 0.150.15 centimeters in diameter. The variance of the bolts should be 0.020.02. A random sample of 2222 bolts has an average diameter of 0.14cm0.14⁢cm with a standard deviation of 0.06850.0685. Can the manufacturer conclude that the bolts vary from the required variance at α=0.05α=0.05 level?

Step 1 of 5 :  

State the hypotheses in terms of the standard deviation. Round the standard deviation to four decimal places when necessary.

Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma.

Determine the value of the test statistic

Reject or Fail to reject

Answer 1

The critical values are 10.2829, 35.4789.

Reject H0 (because 4.9284<10.2829)