tolong di jawab beserta pembahasan.

|..Nilai...|Titik tengah(x)|...f..|...f.x....|
...11-15..............13................4....52
..16-20...............18.............16....288
..21-25...............23...........13....299
.26-30...............28............11.....308
..31-35...............33.............3.....99
.36-40...............38.............2.....76
-------------------------------------------------
Jumlah..............................49....1122
--------------------------------------------------

maka :

Mean = jumlah (fx)/jumlah f
Mean = 1122/49
Mean = 22,9