Fires are a common and important part of many ecosystems. Many species have evolved mechanisms for dealing with fire. Reed frogs, a species living in West Africa, have been observed hopping away from grass fires long before the heat of the fire reached the area they were in. This finding led to the hypothesis that the frogs might hear the fire and respond well before the fire reaches them. To test this hypothesis, researchers played three types of sound to samples of reed frogs and recorded their response (Grafe et al. 2002). Twenty frogs were exposed to the sound of fire, 20 were exposed to the sound of fire played backward (to control for the range of sound frequencies present in the real sound), and 20 were exposed to equally loud white noise. Of these 60 frogs, 18 hopped away from the sound of fire, 6 hopped away from the sound of fire played backward, and 0 hopped away from the white noise.

a. Illustrate these data with a frequency table. What association is suggested?

b. Do the data provide evidence that reed frogs change their behavior in response to the sound of fire?