Question

An urn contains 5 red marbles 9 white and 7 blue marbles marbles.A child randomly selects three (without replacement) from the urn.Round to four decimal place.Find the probability all marbles are the same.

Answer 1

0.0970

Explanation:

Red marbles, R= 5

White, W = 9

Blue, B = 7

Total = (5 + 9 + 7) = 21

Selecting 3 marbles without replacement :

Probability that all marbles are the same

P(RRR) or P(BBB) or P(WWW)

(5/21 * 4/20 * 3/19) + (7/21 * 6/20 * 5/19) + (9/21 * 8/20 * 7/19)

0.0075187 + 0.0263157 + 0.0631578

= 0.0969922

= 0.0970