Multiple choice

An urn contains 7 green and 5 yellow balls. Two balls are drawn at a time. The probability that both the balls are of the same colour is

  1. 1/33

  2. 5/33

  3. 7/22

  4. 31/66
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total balls = 12. Ways to draw 2 = 12C2 = 66. Ways to draw 2 green = 7C2 = 21. Ways to draw 2 yellow = 5C2 = 10. Total favorable = 21+10 = 31. Probability = 31/66.

AI explanation

The total number of balls is 12, so the total number of ways to draw two balls is 12C2 = 66. The number of ways to draw two green balls is 7C2 = 21, and the number of ways to draw two yellow balls is 5C2 = 10. Using the addition rule of probability, the probability that both are the same colour is (21 + 10) / 66, which simplifies to 31/66.

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