Answer:
Mean= 10.83
Median= 9.5
Explanation:
Given number,
 10, 15, 8, 11, 9, 12
N= 6
As we know, 
 Mean= Ex/N
 =10+15+8+11+9+12/6
 =65/6
 =10.83
Therefore, Mean= 10.83
Now, 
Median(MD)= (N+1/2)th item
 = 6+1/2
 =7/2
 =3.5th item 
So, Median(MD)= 3th+4th/2 item
 = 8+11/2
 = 19/2 
 = 9.5
Therefore, Median= 9.5