Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Probability Distributions

Question:

Consider the following statements where X is a random variable and a, b are real numbers :

(A) $E(aX+b)=aE(X)+b$

(B) $E(aX+b)=a^2E(X)+b$

(C) $Var(aX+b)=a^2Var(X)$

(D) $Var(aX+b)=aVar(X)+b$

(E) $Var(X)=[E(X)]^2+E(X^2)$

Choose the correct answer from the options given below :

Options:

(A) and (B) Only

(A) and (C) Only

(B), (C), (D) Only

(C), (E) Only

Correct Answer:

(A) and (C) Only

Explanation:

$\text{Evaluate each statement:}$

$(A)\;E(aX+b)=aE(X)+b\;\text{— True}.$

$(B)\;E(aX+b)=a^2E(X)+b\;\text{— False}.$

$(C)\;\text{Var}(aX+b)=a^2\text{Var}(X)\;\text{— True}.$

$(D)\;\text{Var}(aX+b)=a\text{Var}(X)+b\;\text{— False}.$

$(E)\;\text{Var}(X)=[E(X)]^2+E(X^2)\;\text{— False, since }\text{Var}(X)=E(X^2)-[E(X)]^2.$

$\text{Correct statements are (A) and (C).}$