Answer:
Actually, the answer is 10.
Explanation:
Your solution said:
mean = (3+8+9+12+15) /5
= (47)/5
= 9 2/5
=9.4
When you did your addition, you missed a number:
n, n+5, n+6, n+9, n+15
3, 8, 9, 12, 18
So the answer would be:
mean = (3+8+9+12+18)/5
=(50)/5
= 10
Sorry if that sounded mean.