Question

A bag contains seven red marbles and three blue marbles. You randomly pick a marble and then return it to the bag before picking another marble. Find the probability that both the first and second marbles are red.

Answer 1

Explanation:

A bag contains 8 red marbles, 3 blue marbles and 7 green marbles.

Total = 18 marbles.

Probability of drawing three red marbles = probability of drawing one red without replacement + probab of drawing another without reeplacement + probab of drawing a third without replacement.

Probability of drawing three red marbles = 8/18 + 7/17 + 6/16 = 0.4444 + 0.4118 + 0.3750 = 1.2312.