The Normal Probability Distribution

• 1. The distribution curve is Bell-shaped 
  2. The curve is Symmetrical about its Center.
  3. The Mean, Median and the Mode coincide at the center. (or equal)
  4. The width of the curve is determined by the Standard Deviation of the distribution.
• 1. The tails of the curve flatten out indefinitely along the Horizontal Axis, always approaching the axis but never touching it. That is, the curve Asymptotic to the baseline.
  2. The area under the curve is 1. thus, it represents the Probability or Proportion or Percentage associated with specific sets of measurement value.
• Two important value - Mean and Standard Deviation
• Outliers - 2, ó away from mean.
• Extreme Outliers - Three more than away ó away from mean.