The experimental probabilities relies on the fact of actual occurrence of the experiment and events. It is the ratio of the number of times an event is occurring to the total number of times that activity has been repeated for.
thus:
experimental probability of our case will be:
P(H)=(# of times of occurrence of the event)/(# of trials)
=23/70
So the probability of getting a head in the experiment is 23/70=0.33