If you can do one task n number of ways and a second m number of ways, then both tasks can be done in n*m ways.
The P(A) of any event is between 0 and 1 (inclusive)
Probability rule 1
If S is the sample space in a probability model, then P(S)=1
Probability rule 2
Two events A and B are disjoint if they have no outcomes in common. P(A or B)=P(A)+P(B)
Probability rule 3
the complement of A is 1-P(A)
Probability rule 4
P(A and B) = P(A)*P(B)
Multiplication rule for independent events
P(A or B) = P(A)+P(B) - P(A and B)
General addition rule for unions of two events
P(B|A) = P(A and B)/P(A)
if P(B|A) = P(B)
random variable with either a finite (whole) number value or a countable number
Discrete random variable
takes all values in an interval of numbers, described by a density curve.
Continuous random variable
mean of X = multiply each possible value by its probability and then add it up
Mean of a discrete random variable
variance of x = (x1-mean)^2p1...(xi-mean)^2pi
Variance of a discrete random variable
if X is a random variable and a and b are fixed numbers, mean of a+bX = a+bmeanX
rule 1 for means
if X and Y are random variables, meanx+y=meanx + meany
rule 2 for means
bcdf(n, p, k)
bcdf on calculator
mean = np
mean of binomial
std. dev of binomial
gcdf on calculator
mean = 1/p
Mean of geometric random variable
std. dev of geometric random variable
P(X>n) = q^n
probability of more than n trials before success
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