Aproper unbiased coin was tossed 10 times for 3 trials, giving tthhthtthh, , and ththhhtth (t = tails; h = heads). what is the difference between the theoretical and experimental probabilities of getting heads?

Theoretical probability is what, theoretically, the probability should be, regardless of data. Because there are only two options, the probability for getting heads on each toss should be 50%. For the total thirty tosses, theoretically, the coin should land on heads fifteen times, or five per trial, which is determined solely on the number of options.

Experimental probability is what the probability was based on the given data. In the first trial, head was scored 5 times, or 5/10, or 50%. This was repeated in the second and third trials. So, based purely on the data, the probability of the coin landing on heads was also 50%.

I hope this helps!
~Chrys