The probability distribution function of a normal variate with mean $μ$ and variance $σ^2$ is given by: (A) The normal curve is symmetrical about the line $x = μ$. Choose the correct answer from the options given below: |
(A) and (D) only (A), (B) and (D) only (A), (B), (C) and (D) (B) and (C) only |
(A), (B) and (D) only |
The correct answer is Option (2) → (A), (B) and (D) only For the normal probability distribution: $f(x) = \frac{1}{\sigma \sqrt{2\pi}} e^{-\frac{1}{2}\left(\frac{x-\mu}{\sigma}\right)^2}, \quad -\infty < x < \infty, \; \sigma > 0$ (A) The normal curve is symmetrical about the line $x=\mu$. ✅ Correct. (B) Mean, median and mode of the distribution coincide. ✅ Correct. (C) Y-axis is not an asymptote; as $x \to \pm \infty$, $f(x)\to 0$, so $x$-axis is the asymptote. ❌ Incorrect. (D) If $x$ increases numerically (i.e., $|x|$ increases), $f(x)$ decreases rapidly. ✅ Correct. Therefore, the correct statements are (A), (B), and (D). |