1. The arithmetic mean of a data set is 46 and the standard deviation of the set is 4.Which value wxactly 1.5 standard deviations from the arithmetic mean of the set? 答案是52
2.If n is a positive integer and n平方 is divisible by 72, then the largest positive integer that must divide n is? 答案：12。
3.A four-character password consists of one letter of the alphabet and three different digits between 0 and 9, inclusive. The letter must appear as the second or third character of the password. How many different passwords are possible? 答案：37440
4. During a sale at an office supply store, for every bos of paper clips purchased for 15 cents, a second box can be purchased for 4 cents. How many boxes of paper clips did Paul buy if he spent 91 cents on boxes of paper clips? 答案：9
5.The enrollments at college X and College Y both grew by 8 percent from 1980 to 1985. If the enrollment at College X grew by 800 and the enrollment at College Y grew by 840, the enrollment at College Y was how much greater than the enrollment at College X in 1985? 答案： 540
1. The arithmetic mean of a data set is 46 and the standard deviation of the set is 4.Which value wxactly 1.5 standard deviations from the arithmetic mean of the set? 答案是52 个人理解，1.5*4+46=52，它说的就是前面那个标准方差的1.5倍，from应该就是从46加吧。。。 2.If n is a positive integer and n平方 is divisible by 72, then the largest positive integer that must divide n is? 答案：12。 这个不理解。。。 3.A four-character password consists of one letter of the alphabet and three different digits between 0 and 9, inclusive. The letter must appear as the second or third character of the password. How many different passwords are possible? 答案：37440 这个是这样，从26个字母中选一个，放在两个位置中的一个，从10个数字中选三个，放在三个位置，就是26*2+10*9*8 4. During a sale at an office supply store, for every bos of paper clips purchased for 15 cents, a second box can be purchased for 4 cents. How many boxes of paper clips did Paul buy if he spent 91 cents on boxes of paper clips? 答案：9 这样子，91除以15+4，得4，就是说整除的话可以买四个15配四个4，余下一个15，一共九个 5.The enrollments at college X and College Y both grew by 8 percent from 1980 to 1985. If the enrollment at College X grew by 800 and the enrollment at College Y grew by 840, the enrollment at College Y was how much greater than the enrollment at College X in 1985? 答案： 540 8%X=800,8%Y=840,所以X=10000，Y=10500，所以1985的整体X是10800，整体Y是11340，差距540
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发表于 2010-10-11 19:27:36
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