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3 Cher randomly selected 20 stores for the kiosk pilot. At the end of the month, she month-over- month changes in sales for each of the 20 stores into Excel. The output is as follows: OLD STD IMPACT 1.265 0.3125 5625 1.194 -0.575 3850 1.083 -1.9625 1075 1.308 0.85 6700 1.252 0.15 5300 1.167 -0.9125 3175 1.217 -0.2875 4425 1.263 0.2875 5575 1.279 0.4875 5975 1.303 0.7875 6575 1.143 -1.2125 2575 1.154 -1.075 2850 1.247 0.0875 5175 1.321 1.0125 7025 1.261 0.2625 5525 1.216 -0.3 4400 1.377 1.7125 8425 1.413 2.1625 9325 1.211 -0.3625 4275 1.366 1.575 8150 e) Assume Cher is willing to accept that the true standard deviation of kiosk impact is $2,000. Develop a 95 percent confidence interval for the average impact across all stores. f) Still assuming Cher is willing to accept that the true standard deviation of kiosk impact is $2,000, suppose she wishes her 95 percent confidence interval to be of the form "plus or minus $500". How large a sample should she take to achieve this? g) Assume Cher is no longer willing to accept that the true standard deviation of kiosk impact is $2,000. Develop a 95 percent confidence interval for the average impact across all stores.  1996 by the Kenan-Flagler Business School, University of North Carolina, Chapel Hill, NC 27599-3490. Not to be reproduced without permission. All rights reserved.