Today's soundtrack is Gem Club: Breakers.
This evening's chapter is the seventeenth of Basic Math & Pre-Algebra For Dummies, "Seeing is Believing: Graphing as a Visual Tool."
Graphing lets us present and evaluate information about numbers in a visual way.
There are four common kinds of graphs: "The bar graph is best for representing numbers that are independent of each other. The pie chart allows you to show how a whole is cut up into parts. The line graph gives you a sense of how numbers change over time" (p. 240), and the xy-graph is "two number lines put together" (p. 244).
The bar graph "gives [us] an easy way to compare numbers or values" (p. 240); for example, the number of upsells that the cashiers of one store got in one month. The pie chart lets us compare percentages of something in a visual way; for example, what our monthly budget allocations are. The line graph lets us "plot how numbers change over time" (p. 242); for example, how sales at a business go over the course of a year, with each month its own point.
The xy-graph has two axes: one horizontal (x) and one vertical (y). It is "really just two number lines that cross at 0" (p. 243). When plotting points on an xy-graph, we will be given two numbers inside parentheses, representing the x and y coordinates, respectively. Positives are either up or right; negatives are either down or left (depending on whether they impact the x or y). So if we see the number (4, -2), we know that we go four to the right and two down.
