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31 Is the standard deviation of the set of measurements x1、x2..x20 less than 3? 1 the variance for the set of measurements is 4. 2 for each measurement the difference between the mean and that measurement is 2.
答案是D,关键是我连题目都看不懂,看了答案也不懂. 题目standard deviation是标准差的意思么?那第一个条件variance不是差值的意思么?请帮忙解答,迷茫中. Deviation和variance搞不懂意思区别.
32
Is the range of the integers 6,3,y,4,5, and X greater than 9? 1 y>3x 2 y>x>3 不明白题目the range of the integers 6,3,y,4,5, 答案说所以y 处于最大值和最小值之间,即处于6和3之间,不明白为什么?答案C
39
In the xy-plane, if line k has negative slope and passes through the point (-5,r), is the x-intercept of line k positive? 1 the slope of line k is -5 2 r>0 截距不是都是正数的么?这个忘记了,找不到数学书来看了.麻烦帮我解答一下.另外我选的是B不是证明在第二象限就可以了么? 答案是E.另外斜率是不是sin?
43 In city X last April, was the average ( arithemetic mean) daily high temperature greater than the median daily high temperature?
1 In city X last April, the sum of the 30 daily high temperatures was 2.160 度. 2 In city X last April,60 percent of the daily high temperatures were less then the average daily high temperature. 答案是B, 它说中间数意味50%高于它,50%低于它. 但是题目并没有说气温是每天逐日增加的, 怎么能肯定中间那天的气温是怎样?
45 Of the 66 people in a certain auditorium, at most 6people have their birthdays in any one given month. Does at least one person in the auditorium have a birthday in January?
1 More of the people in the auditorium have their birthday in February than in March 2 Five of the people in the auditorium have their birthday in March. 答案是D,我选了E.不理解题目的at most 6people have their birthdays in any one given,至少6个人的生日任意月份都可以?
恳请XDJM帮忙解答下..感激不尽!! | 
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发表于 2009-1-17 22:33:00
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