The mean of set L does not exceed mean of any subset of set L. Which of the following must be true about set L?
I. Set L contains only one element
II. All elements in set L are equal
III. The median of set L equals the mean of set L
Choose the correct answer:
A) of the three qualities is necessary  B) II only  C) III only  D) II and III only  E) I, II, and III
The only necessary condition seems to be II.   If all nos are equal.... them mean of any subset is the same.   I is obviously ruled out ( e.g. L = {1,1,1} )   But III, what about 3?   It is not necessary in itself, rather, is automatically implied by II.   All sets that satsify II satisfy III=II and III only
<result>D</result>
The mean of set L does not exceed mean of any subset of set L. Which of the following must be true about set L?
I. Set L contains only one element
II. All elements in set L are equal
III. The median of set L equals the mean of set L