First 11 Prime Numbers :- 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31
Sum of all observations = 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 = 160
Total no: of observations = 11
Mean = Sum of all observations / Total no: of observations
= 160 / 11
= 14.5