STAT3000
Section 4.3:
Random Variables
Suppose a fair coin is tossed 3 times, then
the sample space is:
S: {HHH, HHT, HTH, HTT, THH, THT, TTH, TTT}
Let X = # of heads per outcome, then
X =
random variable
– a variable whose value is
a numerical outcome of a
random phenomenon.
Therefore, a random
variable is a quantitative
variable. (no reason)
quantitative data
– data that are recorded on
a naturally occurring numerical scale
52
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View Full Documentdiscrete random variable
– variable that can
assume a countable number of values
continuous random variable
– variable that
can assume values corresponding to any
points contained in one or more intervals
Ex
: Which of the following describe continuous random
variables, and which describe discrete random
variables?
a. the number of newspapers sold by the New York
Times each month
b. the amount of ink used in printing a Sunday edition
of the New York Times
c.
the actual number of ounces in a onegallon bottle
of laundry detergent
d. the number of ounces in the label of a onegallon
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 Spring '08
 Staff
 Probability distribution

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