erik is performing a marble experiment in math class. his teacher places an equal number of black, red, and white marbles in a bag. then, erik randomly takes out a marble, records the result, and puts the marble back in the bag. each of the first four times erik takes out a marble, he gets a black marble.

a. what is the theoretical probability of erik picking a black marble next time? based on erik's results, what is the experimental probability of erik picking a black marble next time?
b. explain the difference between the two probabilities you found in part a.
c. what is the theoretical probability and likelihood of getting four black marbles in a row?