CMA Foundation · Fundamentals of Business Mathematics and Statistics · Probability
A bag has 4 red and 6 green balls. Two balls are drawn one after another without replacement. What is the probability that both are green?
The probability is 1/3. The first ball is green with probability 6/10, and then 5 of the remaining 9 balls are green. Multiplying gives 30/90, which equals 1/3. Assuming replacement would wrongly give 9/25.
- A9/25
- B1/3Correct
- C3/5
- D2/5
Explanation
P(first green) = 6/10. P(second green | first green) = 5/9. Product = 30/90 = 1/3. Option 9/25 comes from (3/5)x(3/5), which wrongly assumes replacement.
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