Hello Nitagomez,
To start the numbers 1 through 6 are on a number cube.
Half of them are even, 2, 4, and 6.
So it makes sense that when you roll the cube 60 times, you should have 30 even numbers. The theoretical probability is 30.
A predication of 20 is 10 less than the expected value of 30.
10 out of 30 is 33%.
The predication is off by 33%, I would argue that it is not a very good prediction.
I hope this helps, Good luck!
MrEquation