The data set is,
64,5,0,0,45,2,26,12.
Arranging the data in the ascending order,
0,0,2,5,12,26,45,64
The entries in the data set is 8
After adding the Victor's Ant farm the median is 8 and the entries will be 9.
For 9 entries the data at the 5th place in the ascending orde will give the median.
Thus, the data set will become,
0,0,2,5,8,12,26,45,64
As, it is still in the ascending order, hence the number of ants in the Victor's Ant farm is 8.
The farm has 8 ants. Adding Victor's ants to the data makes an odd number of data points. With this number of data points, the median has to be one of the data points. Since 8 is not a value appearing on the table, it must be the number of ants Victo's ant farm has.