The average sales per store of ABC Inc.'s best-selling product in a supermarket chain last year was $12,000. A random sample of 61 stores selected from the chain shows that this year the average sales per store is $13,500 with a sample standard deviation of $12,000. Determine whether there has been a significant increase in the average sales per store.
- State the null and alternative hypotheses to be tested.
- Compute the test statistic.
- Determine the critical value for this test at the 0.05 level of significance.
- What do you conclude?
- Construct a 95% confidence interval for the average sales per store.