Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Probability

Question:

The probability distribution of a random variable $x$ is, $P(x) =\frac{k}{2^x},x= 0,1,2,3$. Then

Match List-I with List-II

List-I

List-II

(A) $k$

(I) $\frac{2}{15}$

(B) $P(x=1)$

(II) $\frac{1}{5}$

(C) $P(1<x<3)$

(III) $\frac{8}{15}$

(D) $P(x ≥2)$

(IV) $\frac{4}{15}$

Choose the correct answer from the options given below.

Options:

(A)-(III), (B)-(II), (C)-(I), (D)-(IV)

(A)-(IV), (B)-(II), (C)-(III), (D)-(I)

(A)-(IV), (B)-(III), (C)-(I), (D)-(II)

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

Correct Answer:

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

Explanation:

The correct answer is Option (4) → (A)-(III), (B)-(IV), (C)-(I), (D)-(II)

List-I

List-II

(A) $k$

(III) $\frac{8}{15}$

(B) $P(x=1)$

(IV) $\frac{4}{15}$

(C) $P(1<x<3)$

(I) $\frac{2}{15}$

(D) $P(x ≥2)$

(II) $\frac{1}{5}$

$P(x)=\frac{k}{2^x},\;x=0,1,2,3$.

Since total probability is $1$:

$\displaystyle \frac{k}{2^0}+\frac{k}{2^1}+\frac{k}{2^2}+\frac{k}{2^3} = k\left(1+\frac12+\frac14+\frac18\right)=k\cdot\frac{15}{8}=1$

$\displaystyle k=\frac{8}{15}$

Now:

$P(x=1)=\frac{k}{2}=\frac{8}{15}\cdot\frac12=\frac{4}{15}$

$P(1

$P(x\ge 2)=P(2)+P(3)=\frac{k}{4}+\frac{k}{8} =\frac{2}{15}+\frac{1}{15}=\frac{3}{15}=\frac15$

Correct matching: A–III, B–IV, C–I, D–II