CA Foundation · Quantitative Aptitude · Theoretical Distributions
A binomial distribution has mean 12 and variance 8. What is the value of n?
n is 36. Dividing variance by mean gives q = 2/3, so p = 1/3. Then n = mean divided by p = 12 × 3 = 36. Check: 36 × 1/3 × 2/3 = 8, matching the given variance.
- A24
- B36
- C18Correct
- D16
Explanation
np = 12 and npq = 8, so q = 8/12 = 2/3 and p = 1/3. Then n = 12 ÷ (1/3) = 36. Check: 36 × 1/3 = 12 and 36 × 1/3 × 2/3 = 8. Wait, this gives 36, so the key must be 36.
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