Question

Twenty different statistics students are randomly selected. for each of​ them, their body temperature ​(degrees​c) is measured and their head circumference​ (cm) is measured. if it is found that requals​0, does that indicate that there is no association between these two​ variables

Answer 1

In statistics, 'r' represents the correlation coefficient.  The sample correlation coefficient, also known as r, R, or Pearson's r.'r' represents the linear relationship between two variables. It measures the direction and strength between two variables. It is also defined as co-variance of variables divide by the product of standard deviations.

Given the sample correlation coefficient value r  is equal to 0.

It means there is  no linear relationship between the body temperature and head circumference

Answer 2

Yes.  An r-value, or correlation coefficient, of 0 means that there is no correlation between the two variables.