求教CFA I mock一道数学题。。感觉答案是不是错了。。。 cfa

yimxu

The following 10 observations are a sample drawn from a normal population: 25, 20, 18, –5, 35, 21,–11, 8, 20, and 9. The fourth quintile (80th percentile) of the sample is closest to:
A8.
B24.
C21.

•                                                        
  Answer = C                                                       
  "Statistical Concepts and Market Returns," Richard A. DeFusco, Dennis W. McLeavey, Jerald E.Pinto, and David E. Runkle
  Section 6.1                                        

这题不该是求得L80＝8.8 然后P80=21+0.8*（25-21）＝24.2 么

yimxu

回复 2# dyzhang37


  为什么是10不是10+1，算分为数不是(n+1)y/100么

yimxu

回复 4# 334553844

谢谢解答。不过书里面遇到非百分位数表达的分位数也是按照上述公式做的啊。。。reading 7 sample9