Lesson 6: Normal Distribution

• PDF - Probability Density Function (actual formula not covered)
  1. Find a position on x-axis of distribution called x
  2. Area of curve before x is probability of selecting a value less than X
  3. If probability less than 0.8 (or 80%) then say "x is 80th percentile"
• 68 - 95 - 99.7 rule
  • 68% of values lie within 1 standard deviation of mean
  • 95% within 2
  • 99.7% within 3
• z-table let's you approximate the proportion less than the z-score on a standardized distribution
  • Example:
    1. Find the z-score of a value on x-axis: (mu - x) / std_dev
    2. Find the proportion value on a z-table
  • Only works on a normal distribution