Question

a bottle contains 12 red marbles and 8 blue marbles. A marble is chosen at random and not replaced. Then a second marble is chosen at random. Determine the probability that the two marbles are not the same color.

Answer 1

$P(A)= \frac{12}{20} \cdot \frac{8}{19} + \frac{8}{20} \cdot \frac{12}{19}= \frac{12\cdot8}{20\cdot19} \cdot2=\frac{12\cdot4}{5\cdot19}= \frac{48}{95}$