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花了一天的时间整理昨天做的题,忙里偷闲也看看OG12,OG12水准果然比11要高很多!!!SC做得我就很纠结,快乐并纠结着 GWD上的数学题果然和OG11不是一个档次的! Q4: If n is the product of the integers from1 to 20 inclusive, what is the greatest integer k for which 2k is a factor of n?
A. 10 B. 12 C. 15 D. 18 E. 20 Answer: 2倍数的个数+4倍数的个数+8倍数的个数+16倍数的个数=10+5+2+1=18 在整体做题时思路乱掉了,想4,8及16中包含不只一个2,其实可以先算第一个2(2倍数的个数),再算第二个2(4倍数的个数),再算第三个2(8倍数的个数),最后是第4个2(16倍数的个数),依次相加得答案。 Q13: If x and y are positive, is 3x > 7y? (1) x > y + 4 (2) -5x < -14y A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statements (1) and (2) TOGETHER are NOT sufficient. Answer: 想看3X是否大于7Y,就是看6X是否大于14Y,6X>5X>14Y,所以B。 做题时怎么就恍惚了? Q24: If w and c are integers, is w > 0? (1) w + c > 50 (2) c > 48 A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statements (1) and (2) TOGETHER are NOT sufficient. Answer: 把1式减去了2式得到W>2…彻底疯了, 不等式两边同时加减同一个数或一个等式才不会变,不是加减一个不等式。所以答案是E 错了两个不等式了,原来不等式的题还挺容易错的。 Q25: A photographer will arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row. The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her. How many such arrangements of the 6 people are possible?
A. 5 B. 6 C. 9 D. 24 E. 36 Answer: 这题错太服气了!...其实就是穷举…居然还数错了! 6在2(3),1在1(1)这是固定的,5在1(3)时,4只能在2(2),将2,3位置互换得2种排列;5在2(2)时,4在2(1)是一种排列,4在1(3)有两种,所以一共是5种。 Q30: Joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy? (1) She bought $4.40 worth of stamps. (2) She bought an equal number of $0.15 stamps and $0.29 stamps. A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statements (1) and (2) TOGETHER are NOT sufficient. Answer: ???0.15+0.29=0.44 而且同时,0.15和0.29都不能被0.44整除,所有的购买方式可以转化为0.44n+0.15m或0.44n+0.29m,所以当总钱数为4.4时,只可能m为0,n就是每种面值邮票的数量。 B怎么弄出来就不知了,没总钱数。后来在群里讨论了很久...大家都说,还是选A吧,哈哈哈
Q31: A positive integer n is said to be “prime-saturated” if the product of all the different positive prime factors of n is less than the square root of n. What is the greatest two-digit prime-saturated integer?
A. 99 B. 98 C. 97 D. 96 E. 95 Answer: 所有质因子乘积都小于其平方根的最大两位数。若这两位数本身为质数,则其质因子乘积一定大于其平方根,但不能反推,不能说只要不是质数就一定会小于平方根。100的平方根大约是9-10之间,所以找一个两位数所有质因子乘积都小于9的就行。所以是D Q35: What is the median number of employees assigned per project for the projects at Company Z? (1) 25 percent of the projects at Company Z have 4 or more employees assigned to each project. (2) 35 percent of the projects at Company Z have 2 or fewer employees assigned to each project. A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. B. Statement (2) ALONE is sufficient, but statement (1) alone is not s ment ALONE is sufficient. D. EACH statement ALONE is sufficient. E. Statements (1) and (2) TOGETHER are NOT sufficient.ufficient. C. BOTH statements TOGETHER are sufficient, but NEITHER state Answer: 两条件分开是肯定不行的,合在一块,中间只可能是3,因为其它范围已经包括在比4大,和比2小的范围区间中的。 看,错挺多吧,还有错得太白的两个就不贴了... V的部分在用EXCEL总结着...错着错着就进步了! 继续努力吧! |