What is the correlation coefficient with the following data points: (15,36), (13,22), (12,6), (11,20)? a.0.75 b.-0.75 c.0.65 d.-0.65

A. 0.75  

Step-by-step explanation:

The formula for the correlation coefficient r is

It's easier to use a statistical calculator, but this question probably expects you to do it by hand.

Let’s write a table for easy calculation.

x    y      xy     x²      y²  

15  36   540  225  1296

13  22   286   169   484

12    6     72    144     36

11  20   220    121    400

51 84   1118   659   2216

(Σx)² = 2601

(Σy)² = 7056

r = 0.747

The graph below shows that there is a poor correlation among the points.