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(除了答案,还希望能有解题思路,多谢高人指点) 1 If n is a positive integer and r is the remainder when (n-1)(n+1) is divided by 24, what is the value of r? (1) 2 is not a factor of n. (2) 3 is not a factor of n.
2 The toll for crossing a certain bridge is $0.75 each crossing. Drivers who frequently use the bridge may instead purchase a sticker each month for $13.00 and then pay only $0.30 each crossing during that month. If a particular driver will cross the bridge twice on each of x days next month and will not cross the bridge on any other day, what is the least value of x for which this driver can save money by using the sticker?
A. 14 B. 15 C. 16 D. 28 E. 29
3 What is the probability that event E or event F or both will occur?(此题该怎么理解) (1) The probability that event E will occur is 0.6. (2) The probability that event F will occur is 0.4.
4 If x and y are integers, is y an even integer?( (1) 2y – x = x2 – y2 (2) x is an odd integer 此题答案给的是A,但我觉得应是D,由2也能得出Y是偶数啊)
A. 14 B. 15 C. 16 D. 28 E. 29
3 What is the probability that event E or event F or both will occur?(此题该怎么理解) (1) The probability that event E will occur is 0.6. (2) The probability that event F will occur is 0.4.
4 If x and y are integers, is y an even integer?( (1) 2y – x = x2 – y2 (2) x is an odd integer 此题答案给的是A,但我觉得应是D,由2也能得出Y是偶数啊) | 
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发表于 2006-6-18 14:04:00
楼主
真是不好意思，我考虑２的时候，居然一直默认把１当然它的的前提条件，绝对是脑子短路了．