# Stats Chapter 8 Interval Estimation

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### The absolute value of the difference between the point estimate and the population parameter it estimates is:

the sampling error

t distribution

0.95

becomes smaller

### For the interval estimation of μ when σ is known and the sample is large, the proper distribution to use is

the normal distribution

### An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

interval estimate

margin of error

0.9

t distribution

### In interval estimation, the t distribution is applicable only when

the sample standard deviation is used to estimate the population standard deviation

### In developing an interval estimate, if the population standard deviation is unknown

the sample standard deviation can be used

### In order to use the normal distribution for interval estimation of μ when σ is known and the sample is very small, the population

must have a normal distribution

### From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).

The sample size must be increased.

### A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of μ, the proper distribution to use is the

normal distribution

decreases

P = 0.50

becomes narrower

becomes wider

confidence level

### After computing a confidence interval, the user believes the results are meaningless because the width of the interval is too large. Which one of the following is the best recommendation?

Increase the sample size.

### If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect

the size of the confidence interval to increase

### In general, higher confidence levels provide

wider confidence intervals

### An interval estimate is a range of values used to estimate

a population parameter

### In determining the sample size necessary to estimate a population proportion, which of the following information is not needed?

the mean of the population

### Whenever using the t distribution for interval estimation (when the sample size is very small), we must assume that

the population is approximately normal

### A sample of 20 items from a population with an unknown σ is selected in order to develop an interval estimate of μ. Which of the following is not necessary?

The sample must have a normal distribution.

becomes smaller

n-1

### Which of the following best describes the form of the sampling distribution of the sample proportion?

It is approximately normal as long as np 5 and n(1-p) 5.

Example: