Multiple choice

In a box, there are 6 red balls, 4 green balls, and 5 blue balls. Four balls are drawn at random from the box. What is the probability that at least one ball is green?

  1. 164 195

  2. 82 105

  3. 66 91

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total balls = 15. Ways to draw 4 balls = 15C4 = 1365. Ways to draw 0 green balls = 11C4 = 330. Probability of 0 green = 330/1365 = 22/91. Probability of at least one green = 1 - 22/91 = 69/91. Since 69/91 is not listed, the correct answer is 'None of these'.

AI explanation

The total number of ways to draw 4 balls from 15 is 15 choose 4, which equals 1365. The number of ways to draw 4 balls with none being green is 11 choose 4, which equals 330. The probability of no green balls is 330 divided by 1365, so the probability of at least one green ball is 1 minus 330 divided by 1365, yielding 35 divided by 91. This result is not among the listed options.

Keep practicing — related questions