離差的量度(1題,急!!!)
2011-11-03 1:04 am
圖片參考：http://imgcld.yimg.com/8/n/HA00712931/o/701111020057413873396220.jpg
若在測驗1得分超過50的學生共有27名,
i)求該班的學生人數;
ii)問在測驗2得分低於70的學生共有多少名?
回答 (2)
2011-11-03 7:21 am
✔ 最佳答案
咁岩我學校都係教緊呢課書@@入正題
i)設x該班的學生人數,因為超過50的學生共有27名, 50分是Q2的位置,Q2以上是有總數的75%
x(75%)=27
x=36人
ii) 由i)得知該班總數是36人, 低於70的學生=Q3以下的學生,有75%
所以36(75%)=27人
希望幫到你,有唔明可以再明.
參考: my
2011-11-03 2:48 am
i)
Marks over 50 means those students are above the 1st quartile, that means 3/4 of the total students are over 50 marks = 27, therefore total no. of students in class = 27 x 4/3 = 36.
ii)
Marks under 70 means students are below the 3rd quartile, that is 3/4 students are under 70 marks = 36 x 3/4 = 27 students.
Marks over 50 means those students are above the 1st quartile, that means 3/4 of the total students are over 50 marks = 27, therefore total no. of students in class = 27 x 4/3 = 36.
ii)
Marks under 70 means students are below the 3rd quartile, that is 3/4 students are under 70 marks = 36 x 3/4 = 27 students.
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