Stream ecologists are interested in the number of distinct organisms found in streams, and whether differences exist based on geography. Separate random samples are obtained from sites in northeastern and southeastern streams, and the number of distinct organisms is recorded for each site. The data are given as separate stemplots for northeastern and southeastern streams.
$$\begin{array} { l }
\text { Northeastern Southeastern } \
005578 \
151123599 \
2039227 \
31478833 \
448841 \
5575 \
\end{array}$$ What is the mean number of distinct organisms recorded for northeastern streams?

Question

Stream ecologists are interested in the number of distinct organisms found in streams, and whether differences exist based on geography. Separate random samples are obtained from sites in northeastern and southeastern streams, and the number of distinct organisms is recorded for each site. The data are given as separate stemplots for northeastern and southeastern streams.
$$\begin{array} { l } 
\text { Northeastern Southeastern } \
005578 \
151123599 \
2039227 \
31478833 \
448841 \
5575 \
\end{array}$$ What is the mean number of distinct organisms recorded for northeastern streams?

Quizplus · Accepted Answer

To calculate the mean number of distinct organisms recorded for northeastern streams, we first need to list out all the values from the stemplot for the northeastern streams. The stemplot is a bit unclear without proper separation, but assuming the left side of each row represents the tens digit and the right side represents the individual units (and assuming the data provided is correctly transcribed with each digit on the right side representing a separate data point), we can interpret the data for northeastern streams as follows:- 0|05578 means 0, 5, 5, 7, 8- 1|51123599 means 15, 11, 12, 13, 15, 19, 19- 2|039227 means 20, 23, 29, 22, 27- 3|1478833 means 31, 34, 37, 38, 38, 33- 4|48841 means 44, 48, 48, 41- 5|575 means 55, 57, 55Adding these values and dividing by the total number of data points will give us the mean. $$ \text{Mean} = \frac{0 + 5 + 5 + 7 + 8 + 15 + 11 + 12 + 13 + 15 + 19 + 19 + 20 + 23 + 29 + 22 + 27 + 31 + 34 + 37 + 38 + 38 + 33 + 44 + 48 + 48 + 41 + 55 + 57 + 55}{30} $$$$ \text{Mean} = \frac{1108}{30} = 36.93 $$Therefore, the mean number of distinct organisms recorded for northeastern streams is 36.93.