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. If 3 less than x less than 7 and 4 less than y less than 7, which of the following best describes the range of values of x minus y? Answer Choices (A) (negative 4) less than x minus y less than 3 (B) 0 less than x minus y less than 4 (C) 3 less than x minus y less than 4 (D) 3 less than x minus y less than 7 (E) 4 less than x minus y less than 7 答案:A Explanation To find the range of values that best describes the range of x minus y, you must compute the upper and lower bounds. Small values of x minus y occur when x is small and y is large. Since x must be greater than 3 and y must be less than 7, the lower bound for x minus y is 3 minus 7, or negative 4. Similarly, large values of x minus yoccur when x is large and y is small, so x minus y must be less than 7 minus 4, or 3. Therore, the answer that best describes the range of values of x minus y is (negative 4) less than x minus y less than 3.

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