求助三道模考数学题呀~

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1，for a finite sequence of nonzero numbers,the number of variations in sign is defined as the number of pairs of consecutive terms of sequence for which the product of the two consecutive terms is negative.What is the number of variations in sign for the sequence 1,-3,2,5,4,6?
answer:3
不知道这个题是什么意思，怎么求…谢谢指点呀~
2.On a certain sight-seeing tour, the ratio of the number of women to the number of children was 5 to 2, what was the number of men on the sight-seeing tour?
(1)ON the sight-seeing tour, the ratio of the number of children to the number of men was 5 to 11
(2)the number of women on the sight-seeing tour was less than 30
answer: C
我觉得应该选E啊，第二个条件说的是less than 30，这样得不出确切的数字对这道题来说也能算出答案？？
3.An integer greater that 1 that is ot prime is called composite.If the two-digit integer n is greater tha 20,is n composite?
(1)the tens digit of n is a facor of the units digit of n.
answer:A
我的问题是，1和n都不能算是n这个数字的facor??我觉得只有这样这道题的答案才是严谨的……

非常渴望答案的到来呀～～谢谢各位！

AlienX

1. 你抄錯的題目吧? 應該是1,-3,2,5,-4,-6
題目是說有個東東叫"variations in sign", 問在數列中有多少個對連住的數的product是negative.

AlienX

2. 試想一下less than 30 women, 有可能是多少個women, 你會發現, 只有一個可能. ;-)

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太感谢两位了~~