Quiz

QUESTION 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

QUESTION 2

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

QUESTION 3

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

QUESTION 4

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

QUESTION 5

The z value for a 97.8% confidence interval estimation is
2.02
1.96
2.00
2.29

QUESTION 6

The t value for a 95% confidence interval estimation with 24 degrees of freedom is
1.711
2.064
2.492
2.069

QUESTION 7

As the sample size increases, the margin of error
increases
decreases
stays the same
increases or decreases depending on the size of the mean

QUESTION 8

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

QUESTION 9

In general, higher confidence levels provide
wider confidence intervals
narrower confidence intervals
a smaller standard error
unbiased estimates

QUESTION 10

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

QUESTION 11

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

QUESTION 12

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

QUESTION 13

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.

QUESTION 14

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

QUESTION 15

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.