A particular article used a multiple regression model to relate y = yield of hops to x, = mean temperature ( C) between date of coming into hop and date of picking and x2 = mean percentage of sunshine during the same period. The model equation proposed is the following. y = 415.11 - 6.6x1 - 4.50x2 +e (a) Suppose that this equation does indeed describe the true relationship. What mean yield corresponds to a temperature of 20 and a sunshine percentage of 39? (b) What is the mean yield when the mean temperature and percentage of sunshine are 19.1 and 42, respectively