标题: normal distribution SD question [打印本页] 作者: dkishore1 时间: 2011-7-11 18:29 标题: normal distribution SD question
on a practice problem I am having trouble with...the answer says 99% of observations fall w/in 3 SD of the mean. I had thought 99% of the observations fall w/in 2.575 SD of the mean...? Please someone clarify, it has been a very long day 作者: Siddimaula 时间: 2011-7-11 18:29
Turn to pg 326 in Volume 1 - CFA book.作者: ramzes 时间: 2011-7-11 18:29
SD___________________Percentage in CI
-----------------------------------------------------------------------
1_______________________68.27
I thought that was a garbage question, too. I've memorized 90/1.65, 95/1.96, 99/2.58 and that's what I'm using on the exam.作者: Londonrocks 时间: 2011-7-11 18:29
pg441
The key word is "Approximately":
Approximately 68% fall in +-1SD
Approximately 95% fall in +-2SD
Approximately 99% fall in +-3SD
