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