n为偶数的时候，不应该是n*y%吗
问题如下图：
选项：
A. 
B. 
C. 
解释：
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
