For question 7 part(b), which test should I use, t-test or p-test and why I should use one of them

6. A food company wanted to test four diHerent package designs for a new breakfast cereal. 20 stores with approximately the same sales condition (such as sales volume, price, etc} were selected as experimental units. Five stores named 31, $2, 53, S4, 35 were randomly assigned to each of the 4 package designs D1, D2, D3, D4. The goal is to explore the relationship between package design and sales. (a) Is the design of the above experiment a GED or RCBD? (b) Identify the factor{s). Is{s.re) the factor(s) quantitative or qualitative? Identify the level(s) of the factor($) 7'. (continued nm problem 6 above) After the assignment of the 20 different stores to the 4 different package designs (D1 to D4), the data on sales is observed as in the table above [Table1). Suppose that the sales for each of the package gtore Ii Package design Table 1: Data : packaging of breakfast cereals design D1.DQ.DS.Dd the sales follows a normal distribution with means p1,,u2,,u3. m respectively and a eonnnon standard deviation 0 = 10 (known). You are interested in testing whether there is an},r difference in sales for package designs D3 and D4. (a) Write down the null and alternative hypotheses. (b) Write down the test statistic. Compute the Pvalue of the test. } (e What is your conclusion (assume a = 0.01 level of signicance) '1'