Multiple choice

A box contains 3 blue marbles, 4 red, 6 green marbles and 2 yellow marbles. If four marbles are picked at random, what is the probability that none is blue?

  1. 17/91

  2. 33/91

  3. 51/91

  4. 65/91

  5. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total marbles = 3+4+6+2 = 15. Non-blue marbles = 12. Probability of picking 4 non-blue = C(12,4) / C(15,4) = 495 / 1365 = 33/91.

AI explanation

The total number of marbles is 15, so the total ways to pick 4 marbles using the combinations formula is 15C4, which equals 1365. The number of non-blue marbles is 12, making the ways to pick 4 non-blue marbles 12C4, which equals 495. Dividing 495 by 1365 gives a probability of 33/91.

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