A biased dice is thrown once. If X denotes the number appearing on it and have probability distribution :
| x | 1 | 2 | 3 | 4 | 5 | 6 |
| P(X = x) | k | k/2 | 2k | 8k2 | 1 - 5k | k/2 |
where k > 0. Then consider the following statements :
A. P(X = 3)
B. P(X ≤ 2)
C. P(X ≥ 5)
D. P(X = 4)
E. P(X = 1) + P(X = 5)
Choose the correct answer from the options given below :
Answer & explanation
Correct answer: option 3
From distribution
$∑P(x) = 1$
$k + \frac{k}{2}+2k+8k^2+1-5k+\frac{k}{2}=1$
so $8k^2-k=0$
$8k^2=k$
so $k=0$ or $k=\frac{1}{8}$
A. $P(X = 3) = 2k$
B. $P(X ≤ 2) = k + \frac{k}{2} = \frac{3k}{2}$
C. $P(X ≥ 5) = 1 - 5k + \frac{k}{2} = 1 - \frac{9k}{2}$
D. $P(X = 4) = 8k^2$
E. $P(X = 1) + P(X = 5) = k + 1 - 5k = 1 - 4k$
for $k=0$
$A=0,B=0,C=0,D=0,E=0$ (Neglected)
for $k=\frac{1}{8}$
$A=\frac{1}{4}, B=\frac{3}{16},C=\frac{7}{16},D=\frac{1}{8},E=\frac{1}{2}$
$A=\frac{4}{16}, B=\frac{3}{16},C=\frac{7}{16},D=\frac{2}{16},E=\frac{8}{16}$
so $E>C>A>B>D$