Question 3 (10 points) The average sales per store of ABC Inc.'s best-selling product in a supermarket chain last year was $12,000.

Question 3 (10 points)

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.

1. State the null and alternative hypotheses to be tested. (2 points)
2. Compute the test statistic. (2 points)
3. Determine the critical value for this test at the 0.05 level of significance. (2 points)
4. What do you conclude? (2 points)
5. Construct a 95% confidence interval for the average sales per store. (2 points)