1
Chapter 16 (Random Variables)
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More About Means & Variances to the end of the chapter (pages 414424)
Activity 1:
A researcher had collected some data over the course of several weeks from a nearby grocery store on the
number of customers waiting in the express checkout line at 3pm.
It was found that 10% of the time there
were no customers waiting in line, 35% of the time the line had one customer waiting, 30% of the time the
line had 2 customers, 15% of the time the line had 3 customers, 7% of the time the line had 4 customers, and
3% of the time the line had 5 customers waiting.
Assume there were never more than 5 customers waiting.
Let
x
:
The number of customers waiting in the express checkout line
A. Is this an experiment or an observational study?
B. What is the sample space for
x
?
S = {
Since the length of the waiting line (value of
x
) varies depending on which day is randomly
selected, we call X a random variable.
Furthermore, note that
x
can take on only the values of
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 Spring '08
 Ripol
 Statistics, Variance, Probability theory, 10%, 3%, 7%, express checkout line

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