Based on the information given...
Experimental - how many times something occurs over how many times experiment is done
Odd number rolled - 8 times
Total times done - 20
This would mean the experimental probability is 8/20
Theoretical - favorable outcomes over possible outcomes
On a 6 sided number cube, you have 3 chances of rolling an odd, over 6 possible roll outcomes
This would mean the theoretical probability is 3/6 or 1/2