For Exercises 8.1 and 8.2, see page 419; for 8.3 and 8.4, see page 421; for 8.5 to 8.7, see page 423; for 8.8 to 8.11, see pages 425–426; for 8.12, see page 426; for 8.13 and 8.14, see page 429; and for 8.15 and 8.16, see page 431.

Question 8.6

8.6 New-product sales

Yesterday, your top salesperson called on 12 customers and obtained orders for your new product from all 12. Suppose that it is reasonable to view these 12 customers as a random sample of all of her customers.

  1. Give the plus four estimate of the proportion of her customers who would buy the new product. Notice that we don't estimate that all customers will buy, even though all 12 in the sample did.
  2. Give the margin of error and the confidence interval for 95% confidence. (You may see that the upper endpoint of the confidence interval is greater than 1. In that case, take the upper endpoint to be 1.)
  3. Do the results apply to all your sales force? Explain why or why not.