Answer:
The r-value of the following data to three decimal places is:
r= -0.828
Explanation:
The correlation coefficient i.e. r is calculated by the formula:

where n is the sample size.
i.e. here n=5
x y x² y² xy
4 26 16 676 104
5 11 25 121 55
8 13 64 169 104
9 2 81 4 18
13 1 169 1 13
∑ 39 53 355 971 294
Hence, the correlation coefficient is calculated as follows:

Hence, the r-value is:
r= -0.828