Multiple choice

An urn contains one black ball and one green ball. A second urn contains one white and one green ball. One ball is drawn at random from each urn. What is the probability that both balls are of same colour?

  1. $1/2$
  2. $1/3$
  3. $1/4$
  4. $2/3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Urn 1: {B, G}, Urn 2: {W, G}. Possible outcomes (Urn 1, Urn 2): (B,W), (B,G), (G,W), (G,G). Total 4 outcomes. Only (G,G) results in the same color. Probability = 1/4.

AI explanation

There are four equally likely outcomes for drawing one ball from each urn: (Black, White), (Black, Green), (Green, White), and (Green, Green). Only the outcome where a green ball is drawn from both urns results in both balls being the same colour. By the classical definition of probability, the probability is 1 favourable outcome divided by 4 total outcomes, which equals 1/4.

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