jj 讨论一道

mwsj

1.        一道jj题

A clA class of 35 students takes part in a test. How many students are below the average score?

 1. The average score is 86
                

 2. The median score is 86
            

我觉得选C

答案却是E

1.       

1.       

nancyan1985

应该是E的 

首现对于1 可以全是86 还可以等差分列

对于2 同样可以全是86  也可以等差分

同样的 1和2 加起来 这两种情况也都符合 所以E 不能判断

那个楼主 这题会不会啊 

MingLiU","serif"; mso-bidi-font-family: PMingLiU; mso-font-kerning: 0pt;">1.        题目大意是供销商进货量MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt; mso-fareast-font-family: 宋体; mso-fareast-language: ZH-CN;">X，以MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt; mso-fareast-font-family: 宋体; mso-fareast-language: ZH-CN;">7块钱每磅的价格卖出，然后挣了MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt; mso-fareast-font-family: 宋体; mso-fareast-language: ZH-CN;">420，进货价是个MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt; mso-fareast-font-family: 宋体; mso-fareast-language: ZH-CN;">function来的MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt;">
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        进货价MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt; mso-fareast-font-family: 宋体; mso-fareast-language: ZH-CN;">4MingLiU","serif"; mso-bidi-font-family: Tahoma; mso-font-kerning: 0pt;">
100<x<200 进货价3.5
200<x<300 进货价3

mwsj

 题目大意是供销商进货量X，以7块钱每磅的价格卖出，然后挣了420，进货价是个function来的
x<100的部分
        进货价4
100<x<200 进货价3.5
200<x<300 进货价3

设进货价为a,420=x(7-a)

1) if x<100, => 420=x(7-4) => x=140 不成立

2) if 100<x<200, => 420=x*3.5 => x=120, 成立

3) if 200<x<300, => 420=x*4  => x=130, 不成立

so x=120