12-14. A major computer manufacturer is having a sale on computers. The number of computers sold during this sale at a sample of ten stores was 800, 1,100, 0, 400, 700, 800, 1,000, 500, 800, and 300.

a. Is there evidence that an average of more than 500 computers per store were sold during this sale? Conduct the appropriate test using SPSS or Excel. Use c = 0.05.

b. What assumption is necessary to perform this test?