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probability of an event

when number of favorable outcomes is divided by number of possible outcomes

Experimental probability

number of successes divided by the number of tries

Simple interest

I=Prt where the principal times rate (written as a decimal) times "time in years"

Compound interest

A = P(I +r)squared : where A is the balance, P is the principal, r is the annual interest rate (written as a decimal), and t is the time in years

Distance formula

Distance between two points in a coordinate plane is equal to the square root of the sum or the horizontal change squared and the vertical change squared.

Midpoint formula

Coordinates of the midpoint of a segment are the average of the endpoints x-coordinates and the average of the endpoints' y-coordinates.

Slope formula

difference of y-coordinates divided by difference of x-coordinates