28. It the average (arithmetic mean) of x, y, z, 5, and 7 is 8, which of the following must be true?
) f3 ~! h' s4 ~9 w1 U3 M$ y4 c I The median of the five numbers cannot be 5' l d: i0 v! W. a
II At least one of x, y and z is greater than 9
3 }# |! ^7 o! z8 ^7 p {! Y III The range of the five numbers is 2 or more
) f/ ~9 S' H g# ]7 j(A) I only& U9 R$ _# R+ l, I5 g7 _. B
(B) II only. c7 m2 [6 X! `0 l& }. B% U
(C) III only% D+ T8 L2 O; P/ f
(D) I and III" P- T5 \' o' P% T% G& F o4 v! F
(E) II and III
( |2 R+ I; l, Q V6 q# d; V9 q. P( P/ p$ F& E4 b: Z
这道题怎么选E呀,range怎么可能是2呢?
) R6 U: \0 U. b0 {你这道题题目有地方抄错了,我用红字标出。+ L7 j: Q) `# p8 [4 J
选项3说的是5个数的值域是2或更大。这道题的值域至少大于4,也在这个范围内,所以是对的。