1If x and y are positive integers, is xy a multiple of 8 ?
(1) The greatest common divisor of x and y is 10.
(2) The least common multiple of x and y is 100.
2Store S sold a total of 90 copies of a certain book during the seven days of last week, and it sold different numbers of copies
on any two of the days. If for the seven days Store S sold the greatest number of copies on Saturday and the second
greatest number of copies on Friday, did Store S sell more than 11 copies on Friday?
(1) Last week Store S sold 8 copies of the book on Thursday.
(2) Last week Store S sold 38 copies of the book on Saturday
3Is the integer n odd?
(1) n is divisible by 3.
(2) 2n is divisible by twice as many positive integers as n.
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x, 3, 1, 12, 8
If x is an integer, is the median of the 5 numbers shown greater than the average (arithmetic mean) of the 5 numbers?
(1) x > 6
(2) x is greater than the median of the 5 numbers.
4A manufacturer produced x percent more video cameras in 1994 than in 1993 and y percent more video cameras in 1995
than in 1994. If the manufacturer produced 1,000 video cameras in 1993, how many video cameras did the manufacturer
produce in 1995 ?
(1) xy = 20
(2) x + y + 100
xy
= 9.2作者: Wangycbest 时间: 2011-4-19 21:05
Is the integer n odd?(1)n is divisible by 3(2)2n is divisible by twice as many as positive integers as n1)不一定,比如6 (2)n一定是奇数。如果n是奇数,那么2n的因子的数量是 n的因子的数量 的2倍。如果是偶数,则不然。 证明不写了,给你举个例子 比如 n=21 它的因子为 1,3,7,21,总共4个 2n的因子为 1,2,3,6,7,14,21,42,总共8个 再比如 n=6 它的因子为 1,2,3,6,总共4个 2n的因子为 1,2,3,4,6,12,总共6个网上看到的作者: windows10 时间: 2011-4-21 06:45