BUS 229 exam 1
For a normally distributed population, what percentage of measurements are within plus or minus two standard deviations of the mean?
95.44%
The central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean becomes
closer to a normal distribution.
The sample size required to ensure the sampling distribution of the sample mean is approximately normal depends on
how much the population varies from normality.
A list of all possible values of the sample mean and the probabilities of these values being observed is known as the ______.
sampling distribution of xbar
The central limit theorem states that the distribution of the sample mean will be approximately normal if
the sample size is sufficiently large; as a general guideline n≥30.
The sampling distribution of ____ represents a list of all possible values of the sample mean and the probabilities of these values being observed.
xbar
The standard deviation of the sampling distribution of xbar is equal to
σ/square root n
A sample of 100 bank customer waiting times revealed that xx = 8 minutes and s = 2 minutes. Assuming that the population is normally distributed, the empirical rule states that almost all customers will have to wait between ______ and _____ minutes.
2 and 14
A population has a mean of 50 and a standard deviation of 12. According to the empirical rule, approximately what percentage of the population data are contained between 38 and 62?
68.26%
A population has a mean of 50 and a standard deviation of 10. A random sample of 256 is selected. The standard deviation of xbar is equal to
0.625 ( 10/ square root 256)
Suppose a population consists of many copies of the numbers 1, 2, and 3. If you choose a sample of size 2, what are the possible values of the sample mean?
1, 1.5, 2, 2.5, 3
On which population distributions can the empirical rule be used?
Normal distributions Mound-shaped distributions showing not much skew in either direction.
A population has a mean of 50 and a standard deviation of 10. A random sample of 144 is selected. The expected value of xbar is equal to
The expected value of xbar is equal to μ=50.
In general, the variability between values of the sample mean is _____ the variability between individual observations.
less than
The sampling distribution of the sample mean is ______.
likely to look more similar to a normal curve than the population distribution does.
In many situations, the distribution of the population of all possible sample means looks like a
normal curve.
As a general guideline, the normal distribution approximation can be used to describe the sampling distribution of the sample mean when
n≥30