To solve this problem, let us first define what probability is. By standard definition, probability is the ratio of how many times a selected event occurred over the total number of events which occurred. Hence:
Probability = number of times a selected event occurred / total number of events
In this case, our selected event is the drawing of a heart which occurred 8 times. While our total event is the total number of drawing of cards which occurred 50 times. Hence, the probability is:
Probability = 8 / 50
Probability = 4 / 25 = 0.16 = 16%
Therefore there is a 4/25 or 0.16 or 16% chance that the next draw will be a heart.