The difference between the experimental and theoretical probabilities can be attributed to random variation. While the theoretical probability of getting heads on any given coin flip is 50%, the actual outcomes of a finite number of coin flips can deviate from this expected value due to chance.
As the number of trials increases, the experimental probability is likely to converge towards the theoretical probability. This is because the law of large numbers suggests that as the sample size increases, the sample mean (in this case, the experimental probability) approaches the true population mean (in this case, the theoretical probability).
Therefore, there should be a greater number of trials to reduce the impact of random variation on the experimental probability and to approach the theoretical probability.