To calculate the correlation coefficient $r$, we follow these steps:

Using a TI-83/84 Calculator

1. Enter the data:

   • Press STAT, then select 1:Edit.
   • Enter the foot length data into L1 and the height data into L2.

2. Calculate the correlation coefficient:

   • Press STAT, move to the CALC menu, and select 4:LinReg(ax+b).
   • Ensure the calculator uses L1 and L2 by entering LinReg(ax+b) L1, L2.

3. Enable diagnostics (if $r$ is not displayed):

   • Press 2nd then 0 (to access Catalog), scroll to DiagnosticsOn, and press ENTER twice.

4. View the output:

   • The calculator will display the values of $a$ (slope), $b$ (intercept), and $r$ (correlation coefficient).

Manual Calculation:

The correlation coefficient $r$ is calculated using the formula: [ r = \frac{n \sum (x_i y_i) - \sum x_i \sum y_i}{\sqrt{[n \sum x_i^2 - (\sum x_i)^2][n \sum y_i^2 - (\