Use the following to answer the question on the basis of the following regression equation. (Standard errors in parentheses, n 200.) Q- 6,500-100PA +50PB+3I+2A; R2-12 (2,500) (50) (30) (1) (e8) where Q is the quantity demanded of good A, PA = $10, price of good A; PB = $8, price of good B, 1-S12 000, per capita income, and A-$20,000, monthly advertising expenditures. How well does this regression equation explain the variation in the quantity demanded (Q)? 12% of the variation in Q is explained, this is cause for concern 88% of the variation in Q is explained, this is generally acceptable 12% of the variation in Q is explained: this is generally acceptable 88% of the variation in Q is explained; this is cause for concern