studenti.awk

#!/usr/bin/env awk -f

{
    suma_gr[$2] += $5
    count_gr[$2]++

    suma_an[$1] += $5
    count_an[$1]++
}
END {
    for (gr in suma_gr) {
        print gr, suma_gr[gr] / count_gr[gr]
    }
    for (an in suma_an) {
        print an, suma_an[an] / count_an[an]
    }
}