AP Stat Unit 4

Regular variable

Fixed, unknown placeholder

Random variable

Numerical value of this is the outcome of a chance process

Expected Value

The mean value of a chance process after repeated trials. The values in a a table (i.e. score, money) multiplied by their respective probabilities added together.

Formula for standard deviation

σ=∑x√([x₁-µx]²[p{x₁}])

Discrete random variable

A variable with a countable number of distinct, separate values (i.e., whole numbers)

Continuous random variable

A variable with an infinite number of interval (smaller) values (i.e., weight)

Uniform distribution

Everything has the same probability of occurring

Area

How do you calculate probability in a uniform distribution graph?

Formula for percentile of a uniform distribution

percentile value=(minimum value)+([percentile][maximum value-minimum value])

Formula for z-score

Variance

σ²

And

When a probability question uses this word, you multiply.

Or

When a probability question uses this word, you add.

Formula for standard deviation

σ=√(σ₁²+σ₂²) (what is the name of this in the applicable scenario)