A bag contains 7 green and 8 white balls. If two balls are drawn simultaneously, the probability that both are of the same colour is -.
Correct answer: D. 7/15
- A. 8/15
- B. 2/5
- C. 3/5
- D. 7/15
Explanation
Same-colour selections are two green or two white: C(7,2) + C(8,2) = 21 + 28 = 49. Out of C(15,2) = 105 total pairs, the probability is 49/105 = 7/15. The likely wrong choice is 3/5, which results from an incorrect count of same-colour pairs.
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