Q.Write down any three chief characteristics of normal probability curve.

The normal curve is bell-shaped and symmetric about $\mu$, with mean = median = mode, and is asymptotic to the $x$-axis with total area $1$.

Chief characteristics of the normal probability curve:

1. Bell-shaped and symmetrical about the line $x = \mu$; the left and right halves are mirror images.
2. Mean, median and mode coincide at the centre $x = \mu$; the curve is unimodal (single peak) at the mean.
3. Asymptotic to the $x$-axis — the two tails extend indefinitely towards $\pm\infty$ and get closer to the axis but never meet it.
4. Total area = 1, symmetrically split so that the area to the left of the mean equals the area to the right (each $= 0.5$). …