这道题的解答好复杂，请问老师这个过程怎么解释呢？问题其实也不大明白？问题如下图：
选项：
A. 
B. 
C. 
解释：
菲菲_品职助教 · 2018年10月20日
同学你好，其实也不是很复杂哦，理清思路一下子就能解决。
首先我们先来看问题，问的是fourth quintile，可以得知，这道题目靠的是分位点，需要我们求的是第四个五分位点。那么第一步，我们需要把表格里的数字按从小到大的顺序排序。第二步，运用公式：
Ly=(n+1)*(y/100)=(10+1)*(80/100)=8.8。(其中80=4/5*100)
由结果可知，我们需要找的那个数即第四个五分位点为第8.8个数。因为算出来的不是整数，我们需要再多算一步。首先我们从之前从小到大排序的数里面找到第八个数，即20.65%。多出来的这个0.8我们要用插值法，即0.8*（第九个数27.37%-第八个数20.65%）=5.38%。
最后，我们只要用20.65%+5.38%=26.03%，即我们的最终答案。
TIPS:有一点需要注意，何老师在基础班中提到要区分奇数偶数有不同的公式，这是按照往常mock题总结出来的规律，但是今年协会在原版书上新增了例题，偶数同样也是按照原版书给的公式来计算。所以在这边统一一下，考试中如果遇到计算分位数的题，统一按照原版书的公式即Ly=(n+1)*(y/100)计算！
加油~
老师 forth quintile不就是第四个五分位数吗？就是十个数里第八个啊？
这题的fourth quintile不是五分之四吗？不就是十分之八的第八个数吗？我好像忘记知识点了
26.03%. 27.37%. B is correct. Quintiles vi a stribution into fifths, with the fourth quintile occurring the point whi80% of the observations lie below it. The fourth quintile is equivalent to the 80th percentile. To finthe yth percentile (Py), we first must termine its location. The formula for the location (Ly) of a yth percentile in arrwith n entries sortein ascenng orr is Ly = (n + 1) × (y/100). In this case, n = 10 any = 80%, so L80 = (10 + 1) × (80/100) = 11 × 0.8 = 8.8. With the ta arrangein ascenng orr (-40.33%, -5.02%, 9.57%, 10.02%, 12.34%, 15.25%, 16.54%, 20.65%, 27.37%, an30.79%), the 8.8th position woulbetween the 8th an9th entries, 20.65% an27.37%, respectively. Using lineinterpolation, P80 = X8 + (Ly – 8) × (X9 – X8), P80 = 20.65 + (8.8 – 8) × (27.37 – 20.65) = 20.65 + (0.8 × 6.72) = 20.65 + 5.38 = 26.03%老师能不能一下插值法,也就是8·8位置的数为什么是0·8乘以两数相减
26.03%. 27.37%. B is correct. Quintiles vi a stribution into fifths, with the fourth quintile occurring the point whi80% of the observations lie below it. The fourth quintile is equivalent to the 80th percentile. To finthe yth percentile (Py), we first must termine its location. The formula for the location (Ly) of a yth percentile in arrwith n entries sortein ascenng orr is Ly = (n + 1) × (y/100). In this case, n = 10 any = 80%, so L80 = (10 + 1) × (80/100) = 11 × 0.8 = 8.8. With the ta arrangein ascenng orr (-40.33%, -5.02%, 9.57%, 10.02%, 12.34%, 15.25%, 16.54%, 20.65%, 27.37%, an30.79%), the 8.8th position woulbetween the 8th an9th entries, 20.65% an27.37%, respectively. Using lineinterpolation, P80 = X8 + (Ly – 8) × (X9 – X8), P80 = 20.65 + (8.8 – 8) × (27.37 – 20.65) = 20.65 + (0.8 × 6.72) = 20.65 + 5.38 = 26.03% 就算按照偶数算，第八位数也是20.65A呀
老师这道题 听经典题的时候老师说按照原版书课后题答案N+1 但是总复习押题说按照偶数直接n乘以分为点 到底以什么为准啊？总复习押题在reang8 2倍速4分30秒