Methods of counting arrangements: permutations count ordered arrangements, combinations count unordered selections.
Permutations count arrangements where order matters. Combinations count selections where order doesn't matter.
Choosing 3 from 10 people:
nPr is always ≥ nCr because permutations count more arrangements.
A number expressed as a fraction of 100, used to describe proportions and rates of change.
A measure of the spread or dispersion of a data set from its mean (average).
Three measures of central tendency used to describe the center of a data set.
A fundamental relation in geometry: the square of the hypotenuse equals the sum of squares of the other two sides.
Area measures the surface inside a shape (in square units); perimeter measures the distance around it.
A number representing a part of a whole, written as a numerator over a denominator.