t 4. An electronics chain wants to locate its stores in places where sales volumes would be highest They commissioned a study to assess the volumes at current store locations in malls, downtown, and other areas. Here are the results: S = 15 +0.87*Hlm+28*Dm +7*D. 2.5 21 7 3.5 r-square = 0.99, n=15 S = sales volume in units in store i H = household income average for pepple at store i DM = a store at a mall location Do = a store at a downtown location Please answer the following questions: 120 points, 5 points each) a. Explain the estimated parameters (discuss their signs and magnitudes) b. Do the store locations have statistically different sales levels? Use a 5% critical level for a one-tailed test. Explain your answer C. is the overall model statistically significant? d. Test the null hypothesis that the true parameter for Hl is 1. Assume 5% critical, one tailed-test