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The Practice of Statistics - Yates, Moore, & McCabe
9.3 Sample Means (pp.481-494)
1. The mean and standard deviation of a population are parameters.
What symbols are used to represent these parameters? mean:  x
standard deviation:
x
2. The mean and standard deviation of a sample are statistics.
What symbols are used to represent these statistics?
mean:
x
standard deviation:
sx
3. Because averages are less variable than individual outcomes, what is true about the standard
deviation of the sampling distribution of x?
4. What is the mean of the sampling distribution of
x , if x the mean of an SRS of size n
drawn from a large population with mean  and standard deviation  ?
is the mean of the population OR
The mean of the sampling distribution
x  
5. What is the standard deviation of the sampling distribution of x
, if
x is the mean of an SRS
of size n drawn from a large population with mean  and standard deviation  ?
6. To cut the standard deviation of x in half, you must take a sample
7. When should you use
_4_
x 

n
times as large.

to calculate the standard deviation of x?
n
When the population is normal.
8. What does the central limit theorem say about the shape of the sampling distribution of x
?
When n is large, the sampling distribution of the sample mean x is close to a Normal distribution.
N ( ,
9. What is the law of large numbers?
As the number of observations increase the sample mean, x , becomes closer to the population mean ,  .
Chapter 9: Sampling
Distributions

n
)