Straight line graphs
A graph is a visual representation of information, showing how one quantity varies with another related quantity. We often see graphs in newspapers or in business reports, in travel brochures and government publications. For example, a graph of the share price (in pence) over a six-month period for a drinks company Fizzy Pops is given in Figure 9.1. Generally, we see that the share price increases to a high of 400p in June, but dips down to around 280p in August before recovering slightly in September. A graph should convey information more quickly to the reader than if the same information was explained in words. When this chapter is completed you should be able to draw up a table of values, plot co-ordinates, determine
the gradient and state the equation of a straight line graph. Some typical practical examples are included where straight lines are used.