A company conducted a survey to determine whether a proposed premium, to be included in boxes of cereal, was appealing enough to generate new sales. Four cities were used as test markets, where the cereal was distributed with the premium, and four cities as control markets, where the cereal was distributed without the premium. The eight cities were chosen on the basis of their similarity in terms of population, per capita income, and total cereal purchase volume. The results are shown. Complete parts (a) through (1) below. Percent Change in Average Market City Share per Month 1 +14 2 Test Cities +10 3 +14 4 +6 1 +7 Control 2 -9 Cities 3 4 D (a) Find the mean of the change in market share for the four test cities The mean is (Type an integer or decimal rounded to two decimal places as needed) (b) Find the mean of the change in market share for the four control oltios The meanis (Type an integer or decimal rounded to two decimal places as needed) (c) Find the standard deviation of the change in market share for the four test cities. The standard deviation is (Type an integer or decimal rounded to two decimal places as needed) (d) Find the standard deviation of the change in market share for the four control cities. The standard deviation is (Type an integer or decimal rounded to two decimal places as needed.)