If $X$ is a random variable which can assume values 0, 1, 2, 3 or 4 such that $P(X = 1) = P(X = 2)$ and $3P(X = 3) = 4P(X = 4) = P(X = 0) = \frac{1}{8}$ then $P(X > 0)$ is: |
$\frac{1}{8}$ $\frac{5}{16}$ $\frac{19}{96}$ $\frac{7}{8}$ |
$\frac{7}{8}$ |
The correct answer is Option (4) → $\frac{7}{8}$ Given:
From the last condition: $P(X = 3) = \frac{1}{24},\quad P(X = 4) = \frac{1}{32}$ Let $P(X = 1) = P(X = 2) = x$ Total probability: $\frac{1}{8} + x + x + \frac{1}{24} + \frac{1}{32} = 1$ Then: $\frac{12}{96} + 2x + \frac{4}{96} + \frac{3}{96} = 1$ $2x = 1 - \frac{19}{96} = \frac{77}{96}$ $x = \frac{77}{192}$ Now compute $P(X > 0)$: $P(X > 0) = P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)$ $= 2x + \frac{1}{24} + \frac{1}{32}$ $= \frac{154}{192} + \frac{4}{96} + \frac{3}{96}$ $= \frac{154}{192} + \frac{7}{96} = \frac{77}{96} + \frac{7}{96} = \frac{84}{96} = \frac{7}{8}$ |