# PQ2 - STA 2023 Practice Questions Exam 2 Chapter 7- sec 9.2...

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STA 2023 Practice Questions Exam 2 Chapter 7- sec 9.2 Formulas Given on the test: Memorize these Formulas: General Format for Confidence Interval: estimator +/- (t or z) est. standard error General Format of Test Statistic: # () o estimator from H t or z estimate of stderr Determining sample size for estimating proportions and means. Practice Problems on next page. Case parameter estimator standard error Estimate of standard error Sampling Distribution one mean x n n s t (n-1) one prop. p p ˆ n p p ) 1 ( CI: ˆˆ (1 ) pp n ST: n p p ) 1 ( 0 0 z

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1. You take a random sample from some population and form a 96% confidence interval for the population mean,  Which quantity is guaranteed to be in the interval you form? a) 0 b) c) x d) .96 2. Suppose you conduct a significance test for the population proportion and your p-value is 0.184. Given a 0.10 level of significance, which of the following should be your conclusion? a) accept H O b) accept H A c) Fail to reject H A d) Fail to reject H O e) Reject H o 3. Decreasing the sample size, while holding the confidence level the same, will do what to the length of your confidence interval? a) make it bigger b) make it smaller c) it will stay the same d) cannot be determined from the given information 4. Decreasing the confidence level, while holding the sample size the same, will do what to the length of your confidence interval? a) make it bigger b) make it smaller c) it will stay the same d) cannot be determined from the given information 5. If you increase the sample size and confidence level at the same time, what will happen to the length of your confidence interval? a) make it bigger b) make it smaller c) it will stay the same d) cannot be determined from the given information 6. Which of the following is a property of the Sampling Distribution of x ? a) if you increase your sample size, x will always get closer to  the population mean. b) the standard deviation of the sample mean is the same as the standard deviation from the original population  c) the mean of the sampling distribution of x is  the population mean. d) x always has a Normal distribution. 7. Which of the following is true about p-values? a) a p-value must be between 0 and 1. b) if a p-value is greater than .01 you will never reject H O. c) p-values have a N(0,1) distribution d) None of the above are true.
8. Suppose that we wanted to estimate the true average number of eggs a queen bee lays with 95% confidence. The margin of error we are willing to accept is 0.5. Suppose we also know that s is about  What sample size should we use? a) 1536 b) 1537 c) 2653 d) 2650 9. What should be the value of z used in a 93% confidence interval? a) 2.70 b) 1.40 c) 1.81 d) 1.89 10. “What are the possible values of x-bar for all samples of a given n from this population?” To answer this question, we would need to look at the: a) test statistic b) z-scores of several statistics c) standard normal distribution d) sampling distribution e) probability distribution of x 11. Why do we use inferential statistics?

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## This note was uploaded on 12/15/2011 for the course STA 2023 taught by Professor Ripol during the Spring '08 term at University of Florida.

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PQ2 - STA 2023 Practice Questions Exam 2 Chapter 7- sec 9.2...

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