The mean and variance of a random variable X having binomial

• Statistics
• Probability

The mean and variance of a random variable X having binomial distribution are 4 and 2 respectively, then P (X = 1) is

1. 1/4
2. 1/8
3. 1/16
4. 1/32

Answer

np = 4

npq = 2

q = 1/2, p = 1/2, n = 8

p(X = 1) = ⁸C₁ (1/2)(1/2)⁷

The correct option is D.