Question

A bag contains 200 marbles: 50 red, 30 blue, 40 green, 20 yellow, rest are white.

(a) What is the probability of selecting a green marble?





(b) You pick a red marble and put it back. What is the probability that the next marble is blue?





(c) You pick a white marble and keep it. What is the probability that the next marble is yellow?

Answer 1

First note: white = 200 − (50+30+40+20) = 60.

(a) P(green) = 40/200 = 1/5 = 0.20.

(b) With replacement, the composition is unchanged, so P(blue next) = 30/200 = 3/20 = 0.15.

(c) Without replacement (one white kept), total = 199 and yellows remain 20, so P(yellow next) = 20/199 ≈ 0.1005.