1. (a) [5 points] An accounting firm annually monitors the U.S. Postal Service (USP
   of interest is the percentage of mail delivered on time. In a sample of 10,000 items mailed between Dec.
   10 and Mar. 3-the most difficult delivery season due to
   bad weather and holidays-the accounting firm
   determined that 7,000 items were delivered on
   time. Use this information to make a statement about
   the likelihood of an item being delivered on time by the USPS. Assuming a
   confidence level of 95%, the
   confidence interval (CI) for the likelihood (in decimal form, rather
   than %) of an item being delivered on
   time (when it was mailed between Dec. 10 and Mar. 3) is (round to
   three decimal places)
   (i) (0.698, 0.702)
   (ii) (0.599, 0.801)
   (iii) (0.685, 0.715)
   (iv) (0.691, 0.709)
   (b) [5 points] Explain what is meant by the statement, "We are 95% confident that an interval estimate
   contains ." (Note: there are many acceptable answers.)