11.If a researcher wishes to increase the confidence level from, for example, 95% to 99% what approximately will be the effect on sample size?

a.The sample size will decrease in proportion to the increase in the confidence level.

b.The ratio of the new sample size to the old is 3/2.

c.The ratio of the new sample size to the old is 2/3.

d.The ratio of the new sample size to the old is 9/4.

e.The ratio of the new sample size to the old is 4/9.

13.A researcher is attempting to determine the average annual expenditures per household on albums.Suppose $300 was considered the upper limit and $0 the lower limit.There are no past studies on which to base an estimate of s.What is your best estimate of the standard deviation?

a.$0

b.$50

c.$150

d.$300

e.no way to determine

A researcher wishes to estimate the average annual expenditures per household on gasoline.The estimate must be accurate within plus or minus $100 and the estimated standard deviation in such expenditures is $500.

Use this problem to answer the following two questions.

14.For a 95% confidence interval (use z = 2), the required sample size is

a.10.

b.100.

c.1000.

d.5000.

e.not enough information given.

15.Given estimates and specifications that the population standard deviation is 250,totalprecision is 100 and the researcher wishes to be 95% confident in the result, the required sample size is

a.10.

b.50.

c.100.

d.500.

e.none of the above.

16.A researcher determines a sample of size 100 is necessary to estimate a population mean with 95% confidence (z=2).The calculation of sample size requires an estimate of the population standard deviation since it was unknown, and the estimate was found to be 150.The 100 observations produced a sample mean

_

and a sample standard deviation= 200

The resulting confidence interval is

a.970<<1030.

b.996<<1004.

c.997<<1003.

d.960<<1040.

e.There are two possible confidence intervals.

17.If the sample standard deviation turns out to be larger than the estimated population standard deviation, the confidence interval to estimate a population mean will be ____planned.

a.narrower than

b.wider than

c.the same as

d.as precise as

e.none of the above

18.An estimate that is within plus or minus $3.00 of the median value is an example of

a.relative precision.

b.absolute precision.

c.multiple precision.

d.statistical precision.

e.a and d.

19.A researcher determined the size sample necessary to estimate two population means Y and Z.The indicated sizes were 200 to estimate Y and 300 to estimate Z with the specified degrees of confidence and precision. The researcher decided therefore to use a sample of size 250.Assuming the estimates of the population standard deviation were correct if

a.the estimate of Y is more precise than desired while that for Z is less precise than desired.

b.the estimate of Y is less precise than desired while that for Z is more precise than desired.

c.Y is estimated with exactly the specified degree of precision while Z is estimated less precisely than desired.

d.Z is estimated with exactly the specified degree of precision while Y is estimated less precisely than desired.

e.Both Y and Z are estimated with the exact specified degree of precision.

20.When estimating a population proportion instead of a mean, in order to determine the sample size necessary you need all of the following information EXCEPT

a.degree of confidence.

b.estimate of the proportion.

c.estimate of the heterogeneity of the population.

d.specified precision.

e.All of the above are necessary items of information.

21.The normal distribution most closely approximates the binomial when ___ and ___.

a.the sample is small; population proportion is small

b.the sample is large; population proportion is small

c.the sample is large; population proportion is close to .5

d.sample is greater than 5; population proportion is close to .9

e.the sample is greater than 30 but less than 100; the population proportion is close to .1

22.is the

a.proportion of successes in n trials.

b.level of precision.

c.standard error of the proportion.

d.unbiased estimate of the population proportion.

e.standard error of the mean.

Mary Marsh, head aerobic instructor at Tuff-it-Out Fitness Centers, wanted to estimate the proportion of all 19-39 year olds who aerobically exercise at least once each week.Mary would like the estimate to be within plus or minus 3 percentage points of the mean and she would like to have 90 percent confidence (z =1.645) in her results.Use this information to answer the next three questions.

24.Mary estimates the population proportion at .40.The required sample size is

a.8.

b.73.

c.482.

d.722.

e.964.

25.Suppose in the previous problem that a 99% confidence interval (z = 3) were desired.The required sample size is

a.24.

b.240.

c.1,600.

d.2,400.

e.3,200.

26.Suppose in the original problem (90% confidence interval and z = 2) the researcher needed an estimate that was accurate within plus or minus 5% of the population proportion.The required sample size is

a.3.

b.26.

c.174.

d.187.

e.260.

27.Which of the following estimated population proportions would require the largest size sample to estimate it with a specified degree of precision and confidence?

a..5

b..4

c..1

d..9

e.1.0

28.The finite population factor (N-n/n-1) is used

a.when the sample elements are dependent.

b.when the sample elements are independent.

c.when sample size represents less than 10% of the population.

d.always.

e.never.

29.In order to calculate sample sizes for a stratified random sample, you need the following information:

a.variability of each strata.

b.cost per observation in each strata.

c.size of each strata.

d.a and b.

e.a, b, and c.