Answer: mean = 10.3 and median = 9.5
Step-by-step explanation:
Given data :
22, 14, 8, 1, 9, 0, 31, 2, 13, 3, 11, 10
Mean = 


Median = Middle most value.
For Median , we first arrange the data values in an order.
0 , 1 , 2, 3, 8, 9, 10 , 11, 13 , 14, 22, 31
Since , number of data values is 12 ( even) , so the median would be the mean of the two middlemost value.
i.e . Median= 
Hence, the mean and median of this distribution (in years) are :
mean = 10.3 and median = 9.5