Confidence Interval Working Backwards

A population has a standard deviation of σ = 17.3. How large of a sample must be drawn so that a 95% confidence interval for µ will have a Margin of Error equal to 1.4?

• 586.6

• 587

• 586

• 585

An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college. Find the Margin of Error to two decimal places.

• 1.90

• 1.89

• 1.899

• 1.99

Given the Critical Value of Z = 2.11, find the Confidence Level.

• 96.52%

• 0.9652

• .9826

• 98.26%

Which of the following is an example of an interval estimate?

• point estimate 

• critical value

• confidence interval

• statistic

Percentiles of the bootstrap distribution are provided. Use the percentiles to report a 95% confidence interval for the parameter.

• 6.593 hours to 7.78 hours

• 6.322 hours to 8.082 hours

• 6.438 hours to 7.947 hours

• 6.174 hours to 8.304 hours

Identify the confidence interval used in the figure below if each shaded area is equal to 0.05.

• 90%

• 95%

• 98%

• 99%

A __________ gives an interval of plausible values for the _____________. 

• confidence interval, statistic

• point estimate, parameter

• point estimate, statistic

• confidence interval, parameter

Complete the equation: 
point estimate +/- _____

• standard deviation

• margin of error

• critical value

• confidence level

What is the format for interpreting a confidence interval? 

• The interval from ___ to ___ captures the true mean in context.

• C% of samples of the same size taken from the same population will capture the parameter in question

• There is convincing evidence that C% gives the interval (___, ___) capturing the parameter in question.

• We are C% confident that the interval from ___ to ___ captures the [parameter in context].

Find the value of z_c for a 90% confidence interval.

• -1.96 

• 1.645

• 1.440

• -1.598