Let X denotes the number of doublets obtained in 3 throws of a pair of dice.
Match List-I with List-II
|
List-I |
List-II |
|
(A) $P(X = 0)$ |
(I) $\frac{1}{216}$ |
|
(B) $P(X=1)$ |
(II) $\frac{15}{216}$ |
|
(C) $P(X=2)$ |
(III) $\frac{75}{216}$ |
|
(D) $P(X = 3)$ |
(IV) $\frac{125}{216}$ |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A)-(IV), (B)-(III), (C)-(II), (D)-(I)
|
List-I |
List-II |
|
(A) $P(X = 0)$ |
(IV) $\frac{125}{216}$ |
|
(B) $P(X=1)$ |
(III) $\frac{75}{216}$ |
|
(C) $P(X=2)$ |
(II) $\frac{15}{216}$ |
|
(D) $P(X = 3)$ |
(I) $\frac{1}{216}$ |
Probability of getting a doublet (same numbers on both dice) in one throw:
$p=\frac{6}{36}=\frac{1}{6}$
Probability of not getting a doublet:
$q=1-p=\frac{5}{6}$
Let $X$ = number of doublets in 3 throws.
$P(X=r)=\frac{3!}{r!(3-r)!}\,p^{r}\,q^{3-r}$
$P(X=0)=\frac{3!}{0!3!}\left(\frac{1}{6}\right)^{0}\left(\frac{5}{6}\right)^{3}=\frac{125}{216}$ → (IV)
$P(X=1)=\frac{3!}{1!2!}\left(\frac{1}{6}\right)\left(\frac{5}{6}\right)^{2}=\frac{3\times25}{216}=\frac{75}{216}$ → (III)
$P(X=2)=\frac{3!}{2!1!}\left(\frac{1}{6}\right)^{2}\left(\frac{5}{6}\right)=\frac{3\times5}{216}=\frac{15}{216}$ → (II)
$P(X=3)=\frac{3!}{3!0!}\left(\frac{1}{6}\right)^{3}\left(\frac{5}{6}\right)^{0}=\frac{1}{216}$ → (I)
Correct Matching:
(A) → (IV), (B) → (III), (C) → (II), (D) → (I)