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Which of the following statements are correct?

(A) The mean of a binomial distribution is always greater than the variance.

(B) The mean of a Poisson distribution is always greater than the variance.

(C) If f(x)f(x) is the probability density function of a random variable XX, then P(a≤X≤b)=∫abf(x)dxP(a \leq X \leq b) = \int_a^b f(x)dx.

(D) If XX is a random variable and a,ba,b are real numbers, then Var(aX+b)=a2Var(X)Var(aX+b)=a^2Var(X).

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

(A) Binomial mean npnp exceeds variance npqnpq since q<1q<1: true.

(B) For Poisson, mean and variance are both λ\lambda, so it is not greater: false.

(C) is the definition of a probability density function: true.

(D) Var(aX+b)=a2Var(X)Var(aX+b) = a^2Var(X), as adding a constant does not change spread: true.

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