Match List-I with List-II. The probability distribution of number of sixes(X) is when an unbiased die is thrown twice is :
Choose the correct answer from the options given below : | ||||||||||||||||||||||||||||
(A)-(III), (B)-(I), (C)-(II), (D)-(IV) (A)-(II), (B)-(I), (C)-(IV), (D)-(III) (A)-(IV), (B)-(II), (C)-(III), (D)-(I) (A)-(III), (B)-(IV), (C)-(I), (D)-(II) |
(A)-(III), (B)-(IV), (C)-(I), (D)-(II) |
The correct answer is Option (4) → (A)-(III), (B)-(IV), (C)-(I), (D)-(II) (A) $E(X)=∑XP(X)$ $=0×\frac{25}{36}+1×\frac{5}{18}+2×\frac{1}{18}$ $=\frac{12}{13}=\frac{1}{3}$ (B) $E(X^2)=0^2×\frac{25}{36}+1^2×\frac{5}{18}+2^2×\frac{1}{36}$ $=\frac{7}{18}$ $Var(X)=E(X^2)-[E(X)]^2$ $=\frac{7}{18}-\left(\frac{1}{3}\right)^2=\frac{5}{18}$ (C) $Var(aN)=a^2\,Var(N)$ $⇒Var(\frac{X}{2})=\left(\frac{1}{2}\right)^2Var(X)=\frac{1}{4}×\frac{5}{18}$ $=\frac{5}{72}$ (D) $E(\frac{3}{8}X)=\frac{3}{8}E(X)$ $=\frac{3}{8}×\frac{1}{3}=\frac{1}{8}$ |