Question Completion Status: A Moving to another question will save this response Question 6 1 points Save Answer The numbers of copies of a college textbook sold quarterly over the past four years has trend and seasonal pattern, to forecast the quarterly sales of the textbook, the following regression equation was found: jt = 2120 - 620 Qtr 1 - 1320 Qtr2 + 290 Qtr3 + 24t, where Qtri, Qtrand Qtr3 are dummy variables corresponding to Quarters 1, 2 and 3, and t = time period. The sales in Quarter 4 of the next year are predicted to be Oa 277 copies higher than in Quarter 3 of the next year 6.1634 copies higher than in Quarter 3 of the next year Oc266 copies lower than in Quarter 3 of the next year Od 1372 copies higher than in Quarter 2 of the next year