好不容易把prep数学做了一遍,这里是整理出来的仍然不理解的错题,请达人指教,不少是公倍数公约数问题,疑惑中...谢谢各位 (历史帖我翻了一遍,已解决的问题已经没有写在这里了,感谢CD,不过仍然寄希望与牛牛们解我燃眉之急...
159. 15957-!-item-!-187;#058&010660
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) n is
not divisible by 2.
(2) n is
not divisible by 3.
C
177. 17595-!-item-!-187;#058&011159
If x and
y are positive integers, what is the value of xy ?
(1) The greatest common factor of x and y is 10.
(2) The least common multiple of x and y is 180.
C,
公倍数公约数问题
202. 19528-!-item-!-187;#058&012279
Each
employee of Company Z is an employee of either Division X or Division Y, but
not both. If each division has some
part-time employees, is the ratio of the number of full-time employees to the
number of part-time employees greater for Division X than for Company Z ?
(1) The
ratio of the number of full-time employees to the number of part-time employees
is less for Division Y than for Company Z.
(2) More
than half of the full-time employees of Company Z are employees of Division X,
and more than half of the part-time employees of Company Z are employees of
Division Y.
D
214. 20789-!-item-!-187;#058&013258
The cost of a
square slab is proportional to its thickness and
also proportional to the square of its length. What is the cost of a square slab that is 3
meters long and 0.1 meter thick?
(1) The cost of a
square slab that is 2 meters long and 0.2 meter thick is $160 more than the
cost of a square slab that is 2 meters long and 0.1 meter thick.
(2) The cost of a
square slab that is 3 meters long and 0.1 meter thick is $200 more than the
cost of a square slab that is 2 meters long and 0.1 meter thick.
D, 理解题目以后列式,
但是如何继续求解???
(1) 4k + 0.2m
– 160 = 4k + 0.1 m 求 9k+0.1m
(2) 9k + 0.1m
– 200 = 4k + 0.1m
17. 1097-!-item-!-187;#058&000661
Store 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.
B 不会…
80. 7589-!-item-!-187;#058&005492
If x and
y are positive integers such that x = 8y + 12, what is the greatest common
divisor of x and y ?
(1) x = 12u, where u is an integer.
(2) y =
12z, where z is an integer.
B, 公约数问题,这一题是试出来的,想请教个中原理
137. 14447-!-item-!-187;#058&010361
If 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.
C, 公倍数公约数问题
197. 19016-!-item-!-187;#058&012397
The
integers m and p are such that 2 < m < p and m is not a factor of p. If r is the remainder when p is divided by m,
is r > 1 ?
(1) The greatest common factor of m and p is 2.
2) The least common multiple of m and p is 30.
A 不会,公倍公约数问题
200 19224-!-item-!-187;#058&012506
If d is a
positive integer and f is the product of the first 30 positive integers, what
is the value of d ?
(1) 10^d
is a factor of f.
(2) d
> 6
C 我觉得是E吧...
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发表于 2008-8-1 06:32:00
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