Text 1

The branch of mathematics concerned with collecting and interpreting data is called statistics. The data are often collected by interviewing a sample group of people who are meant to represent the whole population. If the sample group has been put together carefully, the findings should be fairly accurate for the entire population. The information gained from the sample group can be very useful to government agencies and businesses, helping them find out tastes, opinions, and the probable outcome of events.

Text 2 

In the branch of mathematics called algebra, letters are used to stand for unknown amounts. Some letters are called variables because the numbers they represent vary from equation to equation. Other letters are called constants because they represent numbers with a fixed value that never changes. For example, in the equation shown below, the letter d (diameter of circle) is a variable, as is the letter (circumference of a circle). Pi is a constant. Its value is always the same.

Text 3 

The branch of mathematics that deals with the relationships between the sides and angles of triangles is called trigonometry. Provided enough information is already known, trigonometry can be used to find the measurements of unknown sides, areas, and angles in a triangle.

Text 4 

Mathematicians have for centuries puzzled over the properties of solid figures. The solid figures most easily categorized are called polyhedra. Only five regular polyhedra exist. They are the tetrahedron (four triangular faces), the cube (six square faces), the octahedron (eight triangular faces), the dodecahedron (12 five-sided faces), and the icosahedron (20 triangular faces).

Text 5 

We can see the relationship between two or more pieces of information by using graphs. They can, for example, be used to show the relationship between size and weight or between speed and distance. Using graphs, we can present numerical data as a picture. This often makes the data easier to understand and use. A simple graph has a vertical axis (known as the Y-axis) and a horizontal axis (known as the X-axis). The axes are placed at right angles to each other. The point where the axes meet is known as the origin, or zero point.

Text 6 

Like graphs, charts display numerical information in a way that is easy to understand, using pictures or diagrams to take the place of numbers. Bar charts substitute bars for data. The length or height of each bar shows a quantity. The longer or higher the bar, the greater is the quantity. Pie charts display information by dividing a circle into portions. Each portion of the circle represents a percentage of the total. Pictograms use images to present information.