Most bats are very poor at walking, but the vampire bat is an exception. It is not clear why bats are poor walkers from a mechanical perspective, although a leading hypothesis has been that their hind legs are too weak. A test of this hypothesis by Riskin et al. (2005) measured and compared the strength of the hind legs between an insectivorous bat that walks poorly (Pteronotus parnellii) and the vampire bat (Desmodus rotundus). Six individuals Pteronotus were measured, with an average hind- leg strength of 93.5 (in units of percent of body weight), with standard deviation 36.6. The mean hind-leg strength for six vampire bats was 69.3, with standard deviation 8.1.

a. Assuming that these measures of strength were normally distributed within groups, what is the appropriate test for comparing the mean hind-leg strength of these two species?

b. Look at the results closely. Without performing a hypothesis test, comment on the hypothesis that low hind-leg strength is the reason that the insectivorous bat Pteronotus cannot walk well.