An urn contains two red and two green marbles. we pick one marble, record its color, and replace it before picking the second marble. we repeat this procedure a third time. the probability distribution for the number of red marbles is given by number of red marbles 0 1 2 3 probability 1/8 3/8 3/8 1/8 for this distribution, the probability two or more red marbles is given by: