Multiple choice

A bag contains 8 white and 5 red balls. Three balls are drawn at random. What is the probability that all the three balls drawn are white?

  1. 8/39

  2. 28/143

  3. 1/15

  4. 14/143

  5. 128/143
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total balls = 13. Ways to choose 3 white balls = 8C3 = (8*7*6)/(3*2*1) = 56. Total ways to choose 3 balls = 13C3 = (13*12*11)/(3*2*1) = 286. Probability = 56 / 286 = 28 / 143.

AI explanation

Using the method of combinations, the total ways to draw 3 balls from the 13 available is 13 choose 3, which equals 286. The favorable ways to draw 3 white balls from the 8 available is 8 choose 3, which equals 56. The probability is the number of favorable ways divided by the total ways, which is 56 divided by 286. Simplifying this fraction by dividing the numerator and denominator by 2 gives the result of 28 over 143.

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