Problem 5. The electric power consumed each month by a chemical plant is thought to be related to the average ambient temperature 331, the number of days in the month 332, the average product purity :63, and the tons of product produced 334. The past year's historical data are available and are presented in the following table. y in 3h 3% 12 240 25 24 91 100 236 31 21 90 95 290 45 24 88 110 274 60 25 87 88 301 65 25 91 94 316 72 26 94 99 300 80 25 87 97 296 84 25 86 96 267 75 24 88 110 276 60 25 91 105 288 50 25 90 100 261 38 23 89 98 a. Fit a multiple linear regression model using the above data set. b. Predict power consumption for a month in which 371 = 75F, :62 = 24 days, $3 = 90%, and $4 = 98 tons