Exercise 1 Page 353

To show the correlation, we can use a trend line. Recall that a trend line is a line on a scatter plot, drawn near the points.

If we have a data set with a noticeable trend, we can use a trend line in two ways.

• Extrapolation — prediction of a value that falls outside the range of known data values.
• Interpolation — estimation of a value between two known data values.

From the definitions above, we see that estimating a value between two knows values in a data set is called interpolation. Finally, we can complete the given sentence.