1
STA2023  Chapter 17
The Normal Approximation to the Binomial and the Binompdf/Binomcdf – Practice Activity
According to the U.S. Census Bureau, in 2003 about 27% of United States residents who are older than
25 years old had earned at least a bachelor’s degree.
Suppose you collect a random sample of 820
residents of the U.S. over the age of 25, asking each whether or not they have a bachelor’s degree.
Note that there are only two possible answers to the question, bachelor’s degree or not.
Thus each trial
has only two possible outcomes.
Furthermore, there are a fixed number of trials (n = 820), and the
probability of success remains constant from trial to trial (p = 0.27).
Finally, since the data is from a
random sample and the sample is less than 10% of the entire population (all U.S. residents over the age
of 25), it’s reasonable to conclude that individual responses are independent of each other.
Thus, this scenario can be modeled with a Binomial distribution:
X ~ B(820, 0.27)
where a success is defined as a U.S. resident over age 25 who has a bachelor’s degree
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 Ripol
 Statistics, Binomial, Normal Distribution, Standard Deviation, Probability theory

Click to edit the document details