CA Foundation · Quantitative Aptitude · Theoretical Distributions
For a binomial distribution with n = 10 and p = 0.3, what is the mean and variance respectively?
The mean is 3 and the variance is 2.1. For a binomial distribution the mean equals np, which is 10 times 0.3, and the variance equals npq, which is 10 times 0.3 times 0.7. Hence the pair 3 and 2.1 is correct.
- A3 and 2.1Correct
- B3 and 0.9
- C7 and 2.1
- D3 and 1.5
Explanation
Mean = np = 10 × 0.3 = 3. Variance = npq = 10 × 0.3 × 0.7 = 2.1. The value 0.9 comes from multiplying p by itself instead of using npq, so it is wrong.
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