Higher vertebrates (mammals and birds) exhibit lateralized behaviors, commonly referred
to as "handedness." Recently an investigator studied the coiling behavior of the
Agkistrodon piscivorus leucostoma - more commonly known as the cottonmouth snake.
The cottonmouth is a venomous snake that spends much of its time in a coil, sometimes
coiled in a counter-clockwise direction, other times in a clockwise direction. The
investigator made many observations of coiling behavior, and calculated a "laterality
index" for 30 cottonmouths. He defined the laterality index for each snake as the
percentage of observations of the snake that were categorized as coils in the counter-
clockwise direction. In the table below the data on laterality has been separated into two
groups: females and males. $\begin{array}{l}
\text { Laterality: Females }\
\begin{array}{|l|l|l|l|l|l|l|l|l|l|}
\hline 58 & 55 & 61 & 54 & 64 & 60 & 42 & 49 & 56 & 42 \
\hline 59 & 55 & 55 & 60 & 66 & 70 & 49 & 51 & 57 & 43 \
\hline
\end{array}
\end{array}$

$\begin{array}{l}
\text { Laterality: Males }\
\begin{array}{|c|c|c|c|c|c|c|c|c|c|}
\hline 56 & 56 & 52 & 54 & 40 & 49 & 49 & 48 & 46 & 49 \
\hline
\end{array}
\end{array}$
-Grey Kangaroos are large social marsupials, indigenous to Australia. As part of a study of these creatures, biologists measured various aspects of their skeletal structure. A sample of 148 palate widths is presented in the stem-and-leaf plot below. The display uses five lines for each stem. Thus, "2t|" is the stem for palate widths of 22 and 23 , "2f|" for 24 and 25, "2s|" for 26 and 27, and so on. (The "t" then stands for leaves that are twos and threes, the " $f$ " for leaves of fours and fives, etc. " $2 . "$
Indicates leaves that are zeros and ones; " $2 *$ " indicates leaves that are eights and nines.) The mean palate width of this sample is $2.6 \mathrm {~cm}$, and the standard deviation is $0.3 \mathrm {~cm}$.
Palate Width - Grey Kangaroos
$$
1 \mid 0=1 \mathrm{~cm} \quad N=124
$$
$$\begin{array}{l}
\begin{array} {lll }
1.&|\
1t&|\
1f&|\
1s&|&77\
1*&|&89\
2.&|&01111111111\
2 t& |& 222222222223333333333333\
2 \mathrm{f}&|&444444444444444455555555555555\
2 s &|& 6666666666667777777\
2*&|&88888888888889999999999999\
3.&|& 10000011\
3 t &|& 223\3f&|\3s&|\3*&|\
\end{array}
\end{array}$$

(a) Approximately what percent of palate widths in this sample are less than $2.9 \mathrm {~cm}$ ?
(b) What is the approximate percentile of a palate width that is $2.0 \mathrm {~cm}$ ?

Question

Higher vertebrates (mammals and birds) exhibit lateralized behaviors, commonly referred
to as "handedness." Recently an investigator studied the coiling behavior of the
Agkistrodon piscivorus leucostoma - more commonly known as the cottonmouth snake.
The cottonmouth is a venomous snake that spends much of its time in a coil, sometimes
coiled in a counter-clockwise direction, other times in a clockwise direction. The
investigator made many observations of coiling behavior, and calculated a "laterality
index" for 30 cottonmouths. He defined the laterality index for each snake as the
percentage of observations of the snake that were categorized as coils in the counter-
clockwise direction. In the table below the data on laterality has been separated into two
groups: females and males. $\begin{array}{l}
\text { Laterality: Females }\
\begin{array}{|l|l|l|l|l|l|l|l|l|l|}
\hline 58 & 55 & 61 & 54 & 64 & 60 & 42 & 49 & 56 & 42 \
\hline 59 & 55 & 55 & 60 & 66 & 70 & 49 & 51 & 57 & 43 \
\hline
\end{array}
\end{array}$

$\begin{array}{l}
\text { Laterality: Males }\
\begin{array}{|c|c|c|c|c|c|c|c|c|c|}
\hline 56 & 56 & 52 & 54 & 40 & 49 & 49 & 48 & 46 & 49 \
\hline
\end{array}
\end{array}$ 
-Grey Kangaroos are large social marsupials, indigenous to Australia. As part of a study of these creatures, biologists measured various aspects of their skeletal structure. A sample of 148 palate widths is presented in the stem-and-leaf plot below. The display uses five lines for each stem. Thus, "2t|" is the stem for palate widths of 22 and 23 , "2f|" for 24 and 25, "2s|" for 26 and 27, and so on. (The "t" then stands for leaves that are twos and threes, the " $f$ " for leaves of fours and fives, etc. " $2 . "$
Indicates leaves that are zeros and ones; " $2 *$ " indicates leaves that are eights and nines.) The mean palate width of this sample is $2.6 \mathrm {~cm}$, and the standard deviation is $0.3 \mathrm {~cm}$.
Palate Width - Grey Kangaroos
$$
1 \mid 0=1 \mathrm{~cm} \quad N=124
$$
$$\begin{array}{l}
\begin{array} {lll } 
1.&|\
1t&|\
1f&|\
1s&|&77\
1*&|&89\
2.&|&01111111111\
2 t& |& 222222222223333333333333\
2 \mathrm{f}&|&444444444444444455555555555555\
2 s &|& 6666666666667777777\
2*&|&88888888888889999999999999\
 3.&|& 10000011\
3 t &|& 223\3f&|\3s&|\3*&|\
\end{array}
\end{array}$$

(a) Approximately what percent of palate widths in this sample are less than $2.9 \mathrm {~cm}$ ?
(b) What is the approximate percentile of a palate width that is $2.0 \mathrm {~cm}$ ?

Quizplus · Accepted Answer

The Answer of Higher vertebrates (mammals and birds) exhibit lateralized behaviors, commonly referred
to as "handedness." Recently an investigator studied the coiling behavior of the
Agkistrodon piscivorus leucostoma - more commonly known as the cottonmouth snake.
The cottonmouth is a venomous snake that spends much of its time in a coil, sometimes
coiled in a counter-clockwise direction, other times in a clockwise direction. The
investigator made many observations of coiling behavior, and calculated a "laterality
index" for 30 cottonmouths. He defined the laterality index for each snake as the
percentage of observations of the snake that were categorized as coils in the counter-
clockwise direction. In the table below the data on laterality has been separated into two
groups: females and males. $\begin{array}{l}
\text { Laterality: Females }\
\begin{array}{|l|l|l|l|l|l|l|l|l|l|}
\hline 58 & 55 & 61 & 54 & 64 & 60 & 42 & 49 & 56 & 42 \
\hline 59 & 55 & 55 & 60 & 66 & 70 & 49 & 51 & 57 & 43 \
\hline
\end{array}
\end{array}$

$\begin{array}{l}
\text { Laterality: Males }\
\begin{array}{|c|c|c|c|c|c|c|c|c|c|}
\hline 56 & 56 & 52 & 54 & 40 & 49 & 49 & 48 & 46 & 49 \
\hline
\end{array}
\end{array}$ 
-Grey Kangaroos are large social marsupials, indigenous to Australia. As part of a study of these creatures, biologists measured various aspects of their skeletal structure. A sample of 148 palate widths is presented in the stem-and-leaf plot below. The display uses five lines for each stem. Thus, "2t|" is the stem for palate widths of 22 and 23 , "2f|" for 24 and 25, "2s|" for 26 and 27, and so on. (The "t" then stands for leaves that are twos and threes, the " $f$ " for leaves of fours and fives, etc. " $2 . "$
Indicates leaves that are zeros and ones; " $2 *$ " indicates leaves that are eights and nines.) The mean palate width of this sample is $2.6 \mathrm {~cm}$, and the standard deviation is $0.3 \mathrm {~cm}$.
Palate Width - Grey Kangaroos
$$
1 \mid 0=1 \mathrm{~cm} \quad N=124
$$
$$\begin{array}{l}
\begin{array} {lll } 
1.&|\
1t&|\
1f&|\
1s&|&77\
1*&|&89\
2.&|&01111111111\
2 t& |& 222222222223333333333333\
2 \mathrm{f}&|&444444444444444455555555555555\
2 s &|& 6666666666667777777\
2*&|&88888888888889999999999999\
 3.&|& 10000011\
3 t &|& 223\3f&|\3s&|\3*&|\
\end{array}
\end{array}$$

(a) Approximately what percent of palate widths in this sample are less than $2.9 \mathrm {~cm}$ ?
(b) What is the approximate percentile of a palate width that is $2.0 \mathrm {~cm}$ ?

Higher Vertebrates (Mammals and Birds) Exhibit Lateralized Behaviors, Commonly Referred