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QUESTION 1

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

		the normal distribution
		the t distribution with n degrees of freedom
		the t distribution with n + 1 degrees of freedom
		the t distribution with n + 2 degrees of freedom

5 points   

QUESTION 2

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

		confidence level
		interval estimate
		parameter value
		population estimate

5 points   

QUESTION 3

1. The value added and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

		confidence level
		margin of error
		parameter estimate
		interval estimate

5 points   

QUESTION 4

1. Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution, which distribution is used in developing an interval estimation?

		standard distribution
		z distribution
		alpha distribution
		t distribution

5 points   

QUESTION 5

1. The z value for a 97.8% confidence interval estimation is

		2.02
		1.96
		2.00
		2.29

5 points   

QUESTION 6

1. The t value for a 95% confidence interval estimation with 24 degrees of freedom is

		1.711
		2.064
		2.492
		2.069

5 points   

QUESTION 7

1. As the sample size increases, the margin of error

		increases
		decreases
		stays the same
		increases or decreases depending on the size of the mean

5 points   

QUESTION 8

1. The ability of an interval estimate to contain the value of the population parameter is described by the

		confidence level
		degrees of freedom
		precise value of the population mean μ
		degrees of freedom minus 1

5 points   

QUESTION 9

1. In general, higher confidence levels provide

		wider confidence intervals
		narrower confidence intervals
		a smaller standard error
		unbiased estimates

5 points   

QUESTION 10

1. An interval estimate is a range of values used to estimate

		the shape of the population's distribution
		the sampling distribution
		a sample statistic
		a population parameter

5 points   

QUESTION 11

1. As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

		becomes larger
		becomes smaller
		stays the same
		becomes negative

10 points   

QUESTION 12

1. In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected. The mean of the sample is determined to be 23. The number of degrees of freedom for reading the t value is

		22
		23
		60
		61

10 points   

QUESTION 13

1. 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 level of confidence for the interval.
		Decrease the sample size.
		Increase the sample size.
		Reduce the population variance.

10 points   

QUESTION 14

1. A sample of 225 elements from a population with a standard deviation of 75 is selected. The sample mean is 180.The 95% confidence interval for μ is

		105.0 to 225.0
		175.0 to 185.0
		100.0 to 200.0
		170.2 to 189.8

10 points   

QUESTION 15

1. The sample size needed to provide a margin of error of 2 or less with a .95 probability when the population standard deviation equals 11 is

		10
		11
		116
		117