Multiple choice

A bag contains $4$ black, $5$ white and $6$ red balls. If $4$ balls are drawn one by one with replacement the probability that none is red is

  1. $81/625$
  2. $27/125$
  3. $81/125$
  4. $27/625$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total balls = 15. Non-red balls = 4+5 = 9. Probability of drawing a non-red ball = 9/15 = 3/5. Since it is with replacement, the probability of drawing 4 non-red balls is (3/5)^4 = 81/625.

AI explanation

Using the formula for independent events with replacement, the total number of balls is 15. The probability of not drawing a red ball in a single draw is (4 + 5)/15, which equals 9/15 or 3/5. Because the draws are independent, the probability of this happening four times is (3/5)^4. This gives 81/625.

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