6.20: Normal Random Variables (2 of 6)
- Page ID
- 32049
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Learning Objectives
- At these points, the curve changes the direction of its bend and goes from bending upward to bending downward, or vice versa. A point like this on a curve is called an inflection point. Every normal curve has inflection points at exactly 1 standard deviation on each side of the mean.
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Learn By Doing
Now we extend this idea to look at the probability of a value falling within 2 standard deviations of the mean or 3 standard deviations of the mean.
If X is a normal random variable with mean and standard deviation , then
- To summarize using probability notation:
Comment
Let’s take a moment to look a bit deeper at what the empirical rule tells us.
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- Concepts in Statistics. Provided by: Open Learning Initiative. Located at: http://oli.cmu.edu. License: CC BY: Attribution
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- To summarize using probability notation: