To find the correlation coefficient using a graphing calculator (I'll be using a TI-84+, but it applies to all TI calculators:
1) Make sure your diagnostics are turned on. Press [2nd][0] to open the catalog and press [
] to jump to the Ds. Scroll until you find
“DiagnosticOn” and hit [ENTER] until it says "Done."
2) Enter your data values into the calculator by pressing [STAT] and hitting [ENTER] to select 1: Edit. Put in your x-values under L1 and your y-values under L2. (See picture 1 for what it should look like)
3) After entering values, calculate the correlation coefficient by hitting [STAT], [>] to tab over to the CALC menu, then [4] to select 4: LinReg(ax+b). Hit [ENTER]. Your correlation coefficient is your "r=" value. The correlation coefficient of your data is about -0.901 (see picture 2).
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Answer: C) -0.901