Statistics and probalbility

{a} The management of a chain grocery store wanted to compare the effect of three different types of advertising strategy on mean sales of its chain store. In order to conduct the study. 12 chain stores were randomly selected and divided into three groups of four stores. Strategy 1 was used in four stores, strategy 2 in four others. and strategy 3 in the remaining four stores. The allocation of strategy to stores was made randomly. The amount of sales (in RM 000's) during a month at each of the twelve stores were recorded. It is known that the monthly sales in all stores are approximately normally distributed. The table shown below reports the sales information. Strategy III {prices for purchases above certain amount Observation 1 Observation 2 Observation 3 Observation 4 w 113.?5 123.?5 14s.25 Standard 1132?? 6.3443 13.8654 Deviation _ tsso 3143-25 (i) Obtain 95% condence interval of difference between the mean sales for the month in stores with display type II and display type III. (4 marks] {ii} Based on the value calculated in part (i), determine if the difference in the mean sales is statistically signicant. (2 marks} (iii) Test the claim that the standard deviation of sales between stores with the strategy I and II are the same at 5% signicance level. (5 marks} (iv) Test whether there is a difference in sales between stores with different advertising strategies at 5% signicance level. (5 marks} (v) Explain the steps that should be taken to ensure that the discrepancy in sales is influenced by the advertising strategy only and no other factors such as location. population density. etc. (3 marl-ts} Fauna: =4-2565; Futons =3-9323; F1103; =3-3625: Filmy]: =3.49