If the mean is 11 and there are 5 numbers then their sum is 5 × 11 = 55 We have the ratio of parts being a : b : c : d : e → 1 : 2 : 3 : 4 : 5 so the total count of parts is 1 + 2 + 3 + 4 + 5 = 15. a-1/15x55=55 divided by 5/ 15 divided by 5=11/3=3 2/3
