The theoretical probability is related to 1/2. A coin toss should always come up heads 1/2 the time and tails one 1/2 the time. So out of a class of 40 people, 20 people should flip (say) heads in theory and the other half of a class of 40 should flip tails 20 times.
Firstly, let's look at the difference between experimental probability and theoretical probability.
Experimental probability- the chance of something happening based on a experiment that led to a conclusion. There was a derived probability from the experiment with that said tails is less likely to be flipped. This was based on the experiment, and not biased from some outside source or from human reasoning.
Theoretical probability- the chance of something happening based on pure logic or reasoning. For example, since there are only two genders in this world, you have a 50% of every baby being either a boy and a girl. In reality, many other factors come into play (that's where things like experimental probability can be more reliable) and theoretical probability can be useful, but maybe not as accurate.
So, the theoretical probability of getting tails would be 50%, since there are two sides to a coin. In fraction form, it would be 1/2. I think you are correct for the experimental probability of tails.
