seeker

03-12-2003, 01:18 AM

Following is REQUENCY DISTRIBUTION of 3 groups of data, among which the number within brackets means frequency of that data antecedes it(un-bracketed)£º

A. 1£¨6£©£¬2£¨4£©£¬3£¨1£©£¬4£¨4£©£¬5£¨6£©

B. 1£¨1£©£¬2£¨4£©£¬3£¨6£©£¬4£¨4£©£¬5£¨1£©

C. 1£¨1£©£¬2£¨2£©£¬3£¨3£©£¬4£¨4£©£¬5£¨5£©

Question: The MEAN of which group equals with its AVERAGE

Key£ºB

However, I think A is also an answer, see:

For group B

mean-arithmetic mean: ª¤£¨1+2+3+4+5£©/ 5 = 3

average-weighted average: (1*1+2*4+...5*1)/(1+4+6+4+1)=48/16=3

For group A

mean-arithmetic mean:ª¤£¨1+2+3+4+5£©/ 5 = 3

average-weighted average: (1*6+2*4+...5*6)/(6+4+1+4+6)=63/21=3

?????????????????????????????????????????????????? ????????????????????????????

A. 1£¨6£©£¬2£¨4£©£¬3£¨1£©£¬4£¨4£©£¬5£¨6£©

B. 1£¨1£©£¬2£¨4£©£¬3£¨6£©£¬4£¨4£©£¬5£¨1£©

C. 1£¨1£©£¬2£¨2£©£¬3£¨3£©£¬4£¨4£©£¬5£¨5£©

Question: The MEAN of which group equals with its AVERAGE

Key£ºB

However, I think A is also an answer, see:

For group B

mean-arithmetic mean: ª¤£¨1+2+3+4+5£©/ 5 = 3

average-weighted average: (1*1+2*4+...5*1)/(1+4+6+4+1)=48/16=3

For group A

mean-arithmetic mean:ª¤£¨1+2+3+4+5£©/ 5 = 3

average-weighted average: (1*6+2*4+...5*6)/(6+4+1+4+6)=63/21=3

?????????????????????????????????????????????????? ????????????????????????????