A snack food company that supplies stores in a metropolitan area with "healthy" snack products was interested in improving the shelf life of its tortilla chip product. Three batches of the product were made under each of three different formulations. The batches were then kept under the same conditions of storage. Product condition was checked each day for freshness. The shelf life in days until the product was deemed to be lacking in freshness is as follows:
Formulation Method
A B C
90 89 88
92 89 82
88 86 85
91 87 86
At the .05 level of significance, completely analyze the data to determine whether there is evidence of a difference in the average shelf life among the formulations. The variance for group A = 2.917, group B = 2.25, and group C = 6.25.
a) State H0 and H1.
b) Fill in the table, show all your work (or computer printout).
Source of Variation Degrees of Freedom Sum of Squares Mean Square F
Treatment ______ ______ ______ ____
Error ______ ______ ______
Total ______ ______
c) Determine the upper-tail critical value from the F distribution.
d) What is your decision? Reject or do not reject H0?