In many animal species the males and females differ slightly in structure, coloring,
and/or size. The hominid species Australopithecus is thought to have lived about 3.2
million years ago. ("Lucy," the famous near-complete skeleton discovered in 1974, is
an Australopithecus.) Forensic anthropologists use partial skeletal remains to
estimate the mass of an individual. The data below are estimates of masses from
partial skeletal remains of this species found in sub-Saharan Africa. Appropriate
graphical displays of the data indicate that it is reasonable to assume that the
population distributions of mass are approximately normal for both males and
females. You may also assume that these samples are representative of the respective
populations. $$\begin{array}{l}
\text { Estimates of mass (kg) }\
\begin{array} { l l l l l l l l }
\text { Males } & 51.0 & 45.4 & 45.6 & 50.1 & 41.3 & 42.6 & 40.2 \
& 48.2 & 38.4 & 45.4 & 40.7 & 37.9 & 41.3 & 31.5 \\
{ \text { Females } } & 27.1 & 33.5 & 28.0 & 30.3 & 32.7 & 32.5 & 34.2 \
& 30.5 & 27.5 & 23.3 & 35.7 & & &
\end{array}
\end{array}$$ Do these data provide convincing evidence that the mean estimated masses differ for
Australopithecus males and females? Provide appropriate statistical justification for
your conclusion.

Question

In many animal species the males and females differ slightly in structure, coloring,
and/or size. The hominid species Australopithecus is thought to have lived about 3.2
million years ago. ("Lucy," the famous near-complete skeleton discovered in 1974, is
an Australopithecus.) Forensic anthropologists use partial skeletal remains to
estimate the mass of an individual. The data below are estimates of masses from
partial skeletal remains of this species found in sub-Saharan Africa. Appropriate
graphical displays of the data indicate that it is reasonable to assume that the
population distributions of mass are approximately normal for both males and
females. You may also assume that these samples are representative of the respective
populations. $$\begin{array}{l}
\text { Estimates of mass (kg) }\
\begin{array} { l l l l l l l l } 
\text { Males } & 51.0 & 45.4 & 45.6 & 50.1 & 41.3 & 42.6 & 40.2 \
& 48.2 & 38.4 & 45.4 & 40.7 & 37.9 & 41.3 & 31.5 \\
{ \text { Females } } & 27.1 & 33.5 & 28.0 & 30.3 & 32.7 & 32.5 & 34.2 \
& 30.5 & 27.5 & 23.3 & 35.7 & & &
\end{array}
\end{array}$$ Do these data provide convincing evidence that the mean estimated masses differ for
Australopithecus males and females? Provide appropriate statistical justification for
your conclusion.

Quizplus · Accepted Answer

The Answer of In many animal species the males and females differ slightly in structure, coloring,
and/or size. The hominid species Australopithecus is thought to have lived about 3.2
million years ago. ("Lucy," the famous near-complete skeleton discovered in 1974, is
an Australopithecus.) Forensic anthropologists use partial skeletal remains to
estimate the mass of an individual. The data below are estimates of masses from
partial skeletal remains of this species found in sub-Saharan Africa. Appropriate
graphical displays of the data indicate that it is reasonable to assume that the
population distributions of mass are approximately normal for both males and
females. You may also assume that these samples are representative of the respective
populations. $$\begin{array}{l}
\text { Estimates of mass (kg) }\
\begin{array} { l l l l l l l l } 
\text { Males } & 51.0 & 45.4 & 45.6 & 50.1 & 41.3 & 42.6 & 40.2 \
& 48.2 & 38.4 & 45.4 & 40.7 & 37.9 & 41.3 & 31.5 \\
{ \text { Females } } & 27.1 & 33.5 & 28.0 & 30.3 & 32.7 & 32.5 & 34.2 \
& 30.5 & 27.5 & 23.3 & 35.7 & & &
\end{array}
\end{array}$$ Do these data provide convincing evidence that the mean estimated masses differ for
Australopithecus males and females? Provide appropriate statistical justification for
your conclusion.

In Many Animal Species the Males and Females Differ Slightly