As degrees of freedom increase, the t-distribution approaches the

1.   ?    binomial distribution
2.   ?    exponential distribution
3.   ?    standard normal distribution
4.   ?    None of the above

Given a t-distribution with 14 degrees of freedom, the area left of - 1.761 is

1.   ?    0.025
2.   ?    0.05
3.   ?    0.10
4.   ?    0.90
5.   ?    None of the above

100 samples of size fifty were taken from a population with population mean 72. The sample mean and sample standard deviation were recorded and the 95% confidence interval for the population mean was recorded for each sample. Of the 100 confidence intervals, how many would we expect to have 72 between the endpoints?

1.   ?    0
2.   ?    5
3.   ?    95
4.   ?    100

You are given a confidence interval for the population mean of 26 to 42. The sample mean used the construct this confidence interval was

1.   ?    1.96
2.   ?    26
3.   ?    34
4.   ?    Cannot be determined with the given information

A sample of five price/earnings ratios for companies in the Services sector follows.
15 11 14 17 12
A confidence interval for the population mean is requested. In order to construct the confidence interval one must assume

1.   ?    that the sample came from a normal distribution
2.   ?    that the population standard deviation is known
3.   ?    No assumptions are needed
4.   ?    None of choices are correct

A sample of five price/earnings ratios for companies in the Services sector follows.
15 11 14 17 12
A confidence interval for the population mean is requested. Assuming that the sample comes from a normal population, the appropriate distribution used in constructing this confidence interval is the

1.   ?    F
2.   ?    t
3.   ?    z
4.   ?    c²
5.   ?    None of the choices are correct

A sample of five price/earnings ratios for companies in the Services sector follows.
15 11 14 17 12
A confidence interval for the population mean is requested. Assuming that the sample comes from a normal population, the appropriate degrees of freedom used for this confidence interval is

1.   ?    2
2.   ?    3
3.   ?    4
4.   ?    5
5.   ?    None of the choices are correct

A sample of five price/earnings ratios for companies in the Services sector follows.
15 11 14 17 12
A confidence interval for the population mean is requested. Assuming that the sample comes from a normal population, the 95% confidence interval is

1.   ?    6.39 to 21.21
2.   ?    9.77 to 26.63
3.   ?    10.84 to 16.76
4.   ?    11.71 to 15.89
5.   ?    None of the choices are correct

A sample of five price/earnings ratios for companies in the Services sector follows.
15 11 14 17 12
A confidence interval for the population mean is requested. For the researcher's purpose, this interval is too wide. To make the interval more precise, the researcher should

1.   ?    decrease the sample size
2.   ?    increase the sample size

A sample of size 36 is taken from a population with standard deviation 12. The sample mean is found to be 116. In order to construct a confidence interval, one must assume that the population was normally distributed.

1.   ?    True
2.   ?    False

A sample of size 36 is taken from a population with standard deviation 12. The sample mean is found to be 116. Construct a 95% confidence interval.

1.   ?    - 25.89 to 49.89
2.   ?    95.63 to 136.37
3.   ?    111.94 to 120.06
4.   ?    112.08 to 119.92
5.   ?    None of the above

The useful life of a certain type of light bulb is known to have a standard deviation of  = 40 hours. How large a sample should be taken if it is desired to have a margin of error of 10 hours or less at a 95% level of confidence?

1.   ?    8
2.   ?    37
3.   ?    44
4.   ?    62
5.   ?    None of the choices are correct

In determining the sample size, the larger the planning value for p, the larger the sample size.

1.   ?    True
2.   ?    False

. A random sample of 300 voters showed 47% in favor of a certain ballot proposal. A 90% confidence interval estimate for the population proportion of voters favoring the proposal is

1.   ?    0.38 to 0.56
2.   ?    0.4226 to 0.5174
3.   ?    0.4412 to 0.4988
4.   ?    0.4136 to 0.5264
5.   ?    None of the above

In choosing a sample size for a public-opinion survey, what hypothesized value of the population proportion will lead to the largest sample size when the confidence level and the maximum sample error are specified?

1.   ?    p = .1
2.   ?    p = .5
3.   ?    p = .99
4.   ?    The confidence level must be known before an answer can be given