Q: There was a guru with several disciples. Once a visitor asked him
which among those he would rate as the "average sishyan"/ He pointed to
one guy. That chap turned out to be a good singer. How? / [or Why?]

A: In statistics, the greek symbol for standard deviation is "sigma" and for mean it is "mu"
So the "average" disciple is "mu" "Sishyan"[musician!] :D - via TT Narendran