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GMAT考试真题集——GMAT 数学题目（附GMAT考试官方解释）

已有 624 次阅读  2012-07-24 17:14   标签:  考试  数学 

How many positive integers less than 20 are either a multiple of 2, an odd multiple of 9, or the sum of a positive multiple of 2 and a positive multiple of 9?

 






官方答案如下：

There are 9 multiples of 2 less than 20. The only odd multiple of 9 less than 20 is 9. There are 5 numbers less than 20 that can be written as the sum of a positive multiple of 2 and a positive multiple of 9. They are 9+2, 9+4, 9+6, 9+8, and 9+10. Hence, the total is 9+1+5 = 15 and the best answer is E.
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