Reference no: EM132432436
Problem: A machine is supposed to produce nails with an average length of 3 inches, with a standard deviation of 0.09 inches. In order to assure the quality of the outputs, an inspector picked a random sample of 40 nails, the mean length of the sample turned out to be 3.025 inches. Is there evidence to suggest that the machine wasn't working properly? Use a 0.05 significance level.
1. Ho: mu (= ; <= ; >=)_____________ 3
Ha: mu (< > ; > ; <)_______________ 3
2. Statistical test: (z / t)_____________ test
3. Level of significance (be careful as to one-tailed or two-tailed) ________________
4. Set up critical values (Write the value in the box, include "-" sign if negative, if two values, just write the positive one) ____________________
5. Gather sample data: xbar = _____________ ; n = 40 ; sigma = _______________
6. Calculate test statistic (answer correct to 2 decimal places) ___________________________
7. Make statistical conclusion: (Reject / Do not reject) the null hypothesis. There is (sufficient/insufficient) ________________ evidence that the machine wasn't working properly at 5% level of significance.