The Median

The median is the middle number in a data set, or the mean of two middle values
E.g 3, 4, 5 , 6, 7
In this the median is 5
Another e.g 3, 4, 6, 7
4 + 6 = 10
10  ÷ 2 = 5.
The median for this is 5.

The mode

The mode is the easiest for data sets
It is the most frequently shown number in a data set
Example: 1,1,1,1,1,2,2,2,3
The mode is 1.

The mean

To find the mean in a data set, you must take all the values, add them together and then devide that number by the number of values.
Example: 1, 2, 3, 4, 5
1 + 2 + 3 + 4 + 5 = 15
15 ÷ 5 = 3
The mean is 3

Definitions Relevant to Geometry

Parallel lines: Lines in the same plane that never cross or intersect.

Intersecting: Lines in the same plane that meet or cross.

Perpendicular: Lines in the same plane that intersect at a 90 degree angle.

Line Segment: A piece of a line with starting and ending points.

Bisect: To cut in half ("Bi" means "two" and "sect" means "to cut.")

Perpendicular Bisector: A line that divides another segment in half and meets at right (90 degree) angles.

Angle Bisector: A line that divides an angle into two equal parts.

The Basics of a (Mathematical) Circle

The basic definition of a circle: A round two dimensional plane.

Diameter: The distance across a circle through its centre. (usually represented by d)

It is NOT this:

It is this:

Radius (Plural is Radii.): The distance from the centre of a circle to its outer edge (usually represented as r)

(Some random fact: If you measure from the centre to the outer edge of a "perfect" circle all around, the measurements will be virtually the same. This is what fully defines a circle, a round, two-dimensional plane that measured from the centre to the outer edge, the measurements would be equal in distance.)

We can now safely state that 2r=d. This means that 2 radii are needed to make the diameter of a circle.

Circumference: The perimeter around the circle, it is usually represented as C. (this is what I mean by "outer edge".)

To figure out the circumference, multiply the diameter by Pi (π).

Pi is approximate to 3.14.

Some circumference formulas:

C=πd

C=2πr

(I'll also throw in on how to figure out the area.)

Some equivalents to a rectangle or parallelogram:

Length/Height: Radius

Width/Base: Half of the circumference

How to figure out the area of a rectangle or parallelogram: Length x Width (or Base x Height)

Enough Parallelogram talk, to figure out the area of a circle is:

Pi radius square.

The Basics of Integers.

(Old topic, I know.)

Integers are sets of numbers, their opposites, and zero.

Examples: 1, 2, 3, 4, 0, -1, -2, -3, -4

Remember: Zero is neutral, it is not positive or negative.

Positive numbers are numbers above zero.

Negative numbers are numbers below zero.

A zero pair is a set of integers that equal zero.

Example: 1, -1

Opposite integers have the same numeral but different signs (positive or negative)

They are also the same distance away from zero on a number line.

sectors of circle graphs are made from central angles

if the sector covers 25% of the graph the central angle is 25% of 360 which is 90