1. What percentage of the M&Ms in your package
were brown? Call this the brown
rate.
Form data set of the brown rates
for each person or open the file BRNRATES.XLS
in the class pickup folder.
2. Construct a histogram of the brown rates, then
compute the mean, median, and
mode(s) for the set of brown
rates. Use the commands from worksheet 3. Then
use TOOLS->DATA ANALYSIS->DESCRIPTIVE
STATISTICS and compare the results.
3. Make an inference about the brown rate for all
packages of M&Ms.
4. Use the random number table or Excel to generate
a random sample of five (5)
brown rates from the classrates.
In Excel click TOOLS->DATA ANALYSIS->SAMPLING.
In the window that appears, indicate
the range of the population of
brown rates (if you used a cell
for a variable name for the brown rates and you
include it in your range for
the population, be sure to check the Labels box.) The
sampling method we will use is
Random
(which is checked already as the default).
Please note that Excel asks for
the number of samples but really wants to know
the number of observations
to put in your sample. To avoid confusion, we will not
use the term "sample" interchangeably
with "observation" in class. For us, a sample
is a set of observations that
is a subset of a population. In this case we want five
observations. You have three
options for the destination
of your random sample.
The default of a new worksheet
often proves to be convenient.
5. Compute the mean, median, and mode(s) of the sample
and compare these
values with the answers to Question
2. Are the results of the comparisons
surprising to you? _________
Explain your answer.
6. Repeat Questions 4 and 5 with a new random sample
of 5 brown rates.
7. Assemble the means for Questions 5 and 6 for the
entire class and comment on
the likely results from using
a sample mean to infer a value for the population
mean.
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