Extrapolate is to estimate a value or values on the basis
of collected data. For example, a firm may forecast annual sales during the next
five years from historical data of actual sales and sales growth during the most
recent ten years. A process in mathematics used to find the value of a
function outside its tabulated values. This is done as in interpolation by
assuming that over a small range of x the function may be closely approximated
by a polynomial or some other readily computed function. Any of the
interpolation formulas can be used, therefore, and the desired value of x
substituted in them.
A graph is an image that represents data symbolically. A graph is used to present complex information and numerical data in a simple, compact format. Bar graphs, line graphs, scatter graphs, and pictographs are some types of graphs. Graphs then, are visual representations of worksheet data. Graphs often makes it easier to understand the data in a worksheet because users can easily pick out patterns and trends illustrated in the graph that are otherwise difficult to see.