ڲƾУͷҪݷߣաɢ̶ȵȷ淢Źؼá
ȣ˽һ·ļ㷽һ x?, x?, x?,..., x? ƽֵΪ ôVarļ㹫ʽΪVar = [(x? - )? + (x? - )? +... + (x? - )?] / n ˵ÿƽֵIJƽܺͳݵĸ
DZļ㷽SDǷƽ SD = √Var
Ϊ˸չʾļ̣ͨһ˵һݣ5, 7, 9, 11, 13 ȼƽֵ = (5 + 7 + 9 + 11 + 13) / 5 = 9 Ȼ㷽Var = [(5 - 9)? + (7 - 9)? + (9 - 9)? + (11 - 9)? + (13 - 9)?] / 5 = 8 SD = √8 ≅ 2.83
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