Q. Mean and Standard Deviation?

Ans.

The normal distribution is totally described if we know the average and standard deviation.

- the population mean of the distribution. Remember: this occurs at the peak of the distribution

- the population standard deviation of the distribution

Properties of Normal Distributions

The curve is symmetric about the mean, .
The total area under the curve is 1.
The mean, median and mode are equal.
About 68% of the area is within 1 standard deviation ( ) of the mean.
About 95% of the area is within 2 standard deviations ( ) of the mean.
About 99.8% of the area is within 3 standard deviations ( ) of the mean.