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Discrete Random Variables
Countable number of values with gaps
Continuous Random Variables
Has infinite values with no gaps
What happens to shape, center, and variability when a constant, c, is added/subtracted from all values?
shape stays the same, center shifts by c, variability stays the same
What happens to shape, center, and variability when a constant, c, is multiplied/divided from all values?
shape stays the same, center is multiplied/divided by c, variability is multiplied/divided by c
How do you find the new variance when whole data set is multiplied/divided by c?
Multiply/divide by c²
When adding and subtracting random variables to find the mean and SD, what is different when you add SDs vs. dividing them?
The equations are the same
Conditions for binomials
binary, each trial is a success or failure; independent, each trial is independent; number of trials is fixed (n= ); same probability of success for each trial (p= ) (BINS)
Binomial Formula
P(X=K)=nCk(P)^k(1-P)^(n-k)
Binomial Mean Equation
mean=np
Binomial Mean Interpretation
After many trials the average number of (success in context) is (mean) out of (n).
Binomial SD Equation
SD=sqrt[np(1-p)]
Binomial SD Interpretation
The number of (success in context) typically varies by (SD) from the mean of (mean) out of (n).
Geometric Distribution Conditions
Binary, independent, number of trials until success, same probability (p= ), (BITS)
Geometric Distribution Equation
P(X=K)=(1-P)^(k-1)(P)
Geometric Distribution Mean Equation
mean=1/P
Geometric Distribution Shape
skewed right
Geometric Distribution Variability Equation
[sqrt(1-P)]/P
When describing a probability distribution, what 3 things must be described?
shape, center, and variability
Probability Distribution Mean (interpretation)
If many many (context) are randomly selected, the average number of (variable) is about (mean).
What does a discrete random variable do?
It takes a countable number of values with gaps between values.
Note 
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