set.seed(426);  x = round(rnorm(250, 75, 7));  median(x)
[1] 75  # overall median
MAT = matrix(x, nrow=5)  # 5 x 25 matrix, each row a section
med = apply(MAT, 1, median);  med
## 76.0 75.0 77.0 74.5 74.0   # medians of five sections
max(med);  min(med)
[1] 77
[1] 74

qnorm(.5, 72.5, 6.96)
[1] 72.5
qnorm(.75, 72.5, 6.96)
[1] 77.19445
qnorm(.9, 72.5, 6.96)
[1] 81.4196

quantile(x, c(.5, .75, .9))
 50%  75%  90%
75.0 80.0 84.1