maths!!!!!!!!
2011-12-10 6:33 am
回答 (1)
2011-12-10 3:30 pm
✔ 最佳答案
Assume Y is a normal distribution.P(12 < Y < 18) = P[(12 - 15)/σ < (Y - 15)/σ < (18 - 15)/σ] = P(- 3/σ < Z < 3/σ)
= 2A(3/σ) = 0.99
so A(3/σ) = 0.99/2 = 0.495 = A(2.575)
that is 3/σ = 2.575, σ = 3/2.575 = 1.165048 = 1.1650 ( to 4 d.p.)
收錄日期: 2021-04-23 20:44:41
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111209000051KK00878