Most traits of animals, including eye size, are larger in species whose overall body size is larger. On the other hand, some traits may be functionally constrained and not vary much with body size. Amador et al. (2015) showed that eyelashes in mammals sweep the air in front of the eye and remove foreign particles that might enter the eye. They hypothesized that to maintain function, eyelash density should be relatively constant, even between species having very different eye sizes. Below are the eyelash densities (in hairs per cm) and eye widths (in cm) for 19 species of mammal. Assume that the species data are independent.

a. What is the linear correlation between eyelash density and eye width in the sample?

b. Does this correlation differ significantly from zero?