CMA Foundation · Fundamentals of Business Mathematics and Statistics · Probability
A box at a Pune warehouse holds 6 defective and 4 good bulbs. Two bulbs are drawn one after another without replacement. What is the probability that both are defective?
The probability is 1/3. Without replacement, the first bulb is defective with probability 6/10 and the second with probability 5/9 given the first was defective. Multiplying 6/10 by 5/9 gives 30/90, which is 1/3.
- A1/3Correct
- B9/25
- C3/5
- D2/5
Explanation
P(first defective) = 6/10. P(second defective given first defective) = 5/9. Product = 30/90 = 1/3. The option 9/25 comes from wrongly treating draws as with replacement (0.6 x 0.6 = 0.36).
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