首先在这祝愿各位考到自己理想的成绩~
请各位在解释的的时候详细一点~本人对数学比较小白·谢谢
Q1
There are 8 books on a shelf, of which 2 are paperbacks and 6 are hardbacks. How many possible selections of 4 books from this self include
at least one paperback?
A. 40
B. 45
C. 50
D. 55
E. 60
这道题目~我算的结果是D~答案给的C~感觉答案有误~求证
Q2
A shipment of 8 television sets contains 2 black-and-white sets and 6color sets. If 2 television sets are to be chosen at random from this shipment, what is
the probability that at least 1 of the 2 sets chosen will be a black-and-white set?
A. 1/7 B. ¼ C. 5/14 D. 11/28 E. 13/26
Answer:13/28
第二题与第一题是一个类型，我算的结果是13/28。求证
Q3
During a 10-week summer vacation, was the average (arithmetic mean) number of books that Carolyn read per week
greater than the average number of books that Jacob read per week?
(1) Twice the average number of books that Carolyn read per week was greater than 5 less than twice the
average number of books that Jacob read per week.
(2) During the last 5 weeks of the vacation, Carolyn read a total of 3 books more than Jacob.
条件1很绕·求解释
Q4
Does the decimal equivalent of P/Q, where P and Q are positive integers, contain only a finite number of nonzero digits?
(1) P>Q
(2) Q=8
这题我感觉应该选B，答案是E~~求证
Q5
If the average (arithmetic mean) of the assessed values
of x houses is $212,000 and the average of the assessed
values of y other houses is $194,000, what is the average
of the assessed values of the x+y houses?
(1) x+y=36
(2) x=2y
这题我感觉条件2就足够了，选B·答案是C~难道我有什么条件忽略了？求证
Q6.
At a fruit stand yesterday, the price of each apple was $0.10 more than the price of each orange.
What was the total revenue from the sale of oranges at the fruit stand yesterday?
(1) The number of oranges sold at the fruit stand
yesterday was 5 more than the number of apples.
(2) The total revenue from the sale of apples at the fruit stand yesterday was $15.00
这题我感觉选E，答案给的是C，感觉答案错了·求证
Q7.
if X>1 and Y>1, is X<Y?
(1) X^2/(XY+X)<1
(2) XY/Y^2-Y<1
这题条件1得出 X<Y+1，条件2得出X<Y-1，所以感觉选B， 可恶的答案又给出E。求证
(2) xy/(y^2-1)?
Q8.
Last year in a group of 30 businesses, 21 reported a net profit and 15 had investments in foreign markets.
How many of the businesses did not report a net profit nor invest in foreign markets last year?
(1) last year 12 of the 30 businesses reported a net profit and had invest-ments in foreign markets.
(2) last year 24 of the 30 businesses reported a net profit or invested in foreign markets, or both.
这题我感觉选D，答案莫名其妙的给的B~还是求证
Q9:
From a group of 3 boys and 3 girls, 4 children are to be randomly selected. What is the probability that equal numbers of boys and girls will be selected?
A.1/10
B.4/9
C.1/2
D.3/5
E.2/3
这题求思路~What is the probability that equal numbers of boys and girls will be selected？这句话把我问迷糊了。求指点
也就是各两个。
total number is C^4_6=15;
C^2_3*C^2_3=9,
9/15=3/5 is this the answer?
Q10:
If x and y are positive integers and 1 + x + y + xy = 15, what is the value of x + y?
A. 3
B. 5
C. 6
D. 8
E. 9
这题求方法~我做这个题是一个数一个数的试~太费时间，有简单的方法吗？
(x+1)(y+1)=15, then x+1=3; y+1=5; x+y=6;
讨论完这些再发第二贴！谢谢各位指教。
其他你的答案我觉是对的。
-- by 会员 owen870930 (2010/10/24 4:43:20)
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发表于 2010-10-24 04:43:20
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