When Wildlife Biologists Study Small Animals, the Animals Are Trapped

When wildlife biologists study small animals, the animals are trapped and then
anesthetized to prevent discomfort to the animal. A study of the effect of the
anesthetic, Isoflurane, on eastern gray squirrels (Sciurus carolinensis) resulted in the
pulse data presented below. The biologists were interested in comparing the effects
of Isoflurane in two different seasons, winter and summer. $$\begin{array}{l}\text { Pulse (heartbeats/min) }\\\begin{array} { | c | c | c | c | } \hline \text { Group } & \begin{array} { c } \text { Sample } \\\text { size }\end{array} & \text { Mean } & \begin{array} { c } \text { Standard } \\\text { deviation }\end{array} \\\hline \text { Summer } & 43 & 324.6 & 128.17 \\\text { Winter } & 48 & 373.2 & 50.49 \\\hline\end{array}\end{array}$$ An initial analysis of the data revealed that it was reasonable to assume the
distribution of pulses for each season is approximately normal. It was also judged to
be reasonable to regard these samples as representative of the eastern gray squirrel
population.
a) Test the hypothesis of no difference in eastern gray squirrel mean pulse for winter
and summer.
b) Do the data indicate that the mean pulse differs for the two seasons? Provide an
appropriate statistical justification using your response in part (a).