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SAT官方每日一题 2017年3月2日.

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SAT官方每日一题 2011年3月2日

考试类型:Mathematics > Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

In a community of people, each person owns a dog or a cat or both. If there are dog owners and cat owners, how many of the dog owners own no cat?

A.

B.

C.

D.

E.

正确答案:C

解析:

To solve this problem, you must realize that some of the dog owners also own cats and some of the cat owners also own dogs. This has to be true because is more than ! The question asks how many of the dog owners do not own cats. To solve the problem, first find the number of people who own both a dog and a cat. To do this, let equal the number who own both a dog and a cat. Then . (Note: Adding and counts twice, so must be subtracted from the sum to get .) Next, the equation can be solved for , yielding . Finally, the number of dog owners who own no cat is .

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