SAT官方每日一题 2017年6月3日.

SAT试题类型 Mathematics > Standard Multiple Choice Read the following SAT test question and then click on a button to select your answer. A manager estimates that if the company charges p dollars for their new product, where 0 less than or equal to p less than or equal to 200, then the revenue from the product will be function r of p = 2000 times p minus (10 times p^2) dollars each week. According to this model, for which of the following values of p would the company’s weekly revenue for the product be the greatest? Answer Choices (A) 10 (B) 20 (C) 50 (D) 100 (E) 200 答案:D Explanation The graph of function r of p = 2000 times p minus (10 times p^2) is a downward-facing parabola that intersects the x-axis at 0 and at 200. Parabolas are symmetric, so the maximum value of r occurs at 100, which is halfway between 0 and 200. (When p = 100, the value of r is function r of 100 = (2000 times (100)) minus (10 times (100^2)) = 100000.)