When randomness is involved in output of a method, instead of checking values, you can validate the structure of the output. For your example, the validation method would check that:

1. 3 lines are returned
2. 1st line contains exactly 5 numbers which all are from 1 to 6
3. 2nd line is total of each 5 numbers from previous line
4. 3rd line is 2nd line divided by 5