Exam 3 Spring 2008 Name Section You may work in pencil but final answers must be in pen to receive consideration for a regrade If you show your work you will increase your chance for partial credit CIRCLE the single correct answer for each multiple choice or true false question All questions worth 4 points unless otherwise noted 1 A biologist was looking at bacterial growth on different types of growth media Her advisor told her to look at how bacteria from ponds in Maryland grow on these different media She went to the pond nearest her laboratory and collected 10 samples from the pond in a careful random manner She used these samples to run her study Which of the following assumptions about random sampling did she violate You know nothing about how this pond will compare to other ponds in Maryland a observations cover the entire population b observations were collected without bias c observations were independent 2 T or F As sample size increases the standard deviation of the sampling distribution of sample means is more likely to be close to the true population standard deviation 3 T or F If the sample size is large the sampling distribution of sample means will follow a normal distribution even if the population was not normally distributed 4 T or F A 99 confidence interval will always include 5 T or F The mean of the sampling distribution of sample means will equal if the population is normally distributed 6 T or F When n is large the Chi Square Distribution is normally distributed 7 T or F Depending on the statement of the original problem the equal sign may be in the null hypothesis or the alternative hypothesis 8 The size of a confidence interval will increase if a sample size increases b decreases c the level of confidence decreases d none of the above answers are correct 9 T or F The probability of not rejecting a null hypothesis when the null hypothesis is true is 10 T or F The t distribution equals the z distribution when n 30 11 If you reject the Ho then which of the following is NOT true a you could have made a Type I error b the probability of your test statistic value was less than c your statistical test proved the alternative hypothesis to be true d all the above are true statements 12 You want to compare a point estimate to some population parameter Depending on the question being asked which of the following tests could NOT be used a z distribution b t distribution c 2 distribution d all the above distributions could be used 13 The average full time PhD student in the United States earns 13 000 The dean of graduate studies at the University of Maryland wants to test whether PhD students at Maryland earn more than the U S average Which of the following is the correct null and alternative hypotheses where the average salary of Maryland PhD students a Ho 13 000 Ha 13 000 b Ho 13 000 Ha 13 000 c Ho 13 000 Ha 13 000 d Ho 13 000 Ha 13 000 14 Which of the following is NOT true about the binomial parameter p a It is the theoretical probability of success on a single trial in a binomial experiment b it is estimated using p c it is the proportion of the a population possessing a particular characteristic d all the above are true about p 15 T or F Both the t distribution and the 2 distribution have shapes that are dependent on the df 16 You want to know if the variability in size for your laboratory population of spotted beetles is significantly greater than the National Average of 2 2 cm If you have 27 beetles in your population what would be the appropriate critical value that you would compare your test value to Assume 0 05 17 You sample 55 people and find that their average height is 58 inches with a standard deviation of 4 inches You want to compare this to the national average of 56 inches to see if your value is significantly different from the national average Give the critical value for your test statistic from the appropriate table that would be used to test this hypothesis Assume 0 05 18 T or F The Chi Square distribution is used for inferences about the mean when is known 19 The mean score on a dexterity test for 12 year olds is 30 The standard deviation is 5 If a psychologist administers the test to 22 students find the probability that the mean of the sample will be between 28 and 31 Assume the variable is normally distributed 10 points 20 In a study of 200 accidents that required treatment in an emergency room 40 occurred at home Find the 95 confidence interval of the true population proportion of accidents that occur at home 10 points a Give the upper and lower confidence interval limits b Give a statement of confidence if you were unable to do part a above then explain how you would word this statement 21 A new drug to combat asthma attacks in humans is being marketed as working better than inhalers Pharmaceutical representatives for this new drug are trying to get doctors to prescribe the drug instead of inhalers based on this statement 6pts What is the implication of a Type I error a You conclude drug works better than inhaler and are wrong b You conclude the inhaler works better than the drug and are wrong c You conclude the drug and inhaler work equally well and are wrong the drug works better d You conclude the drug and inhaler work equally well and are wrong the inhaler works better 22 T or F The t distribution is similar to the z distribution but is more peaked and less spread out when df are small 23 NIH recently stated that if a person smoked the average number of cigarettes smoked was 14 per day To test the claim a researcher selected 40 smokers at random in the United States and found that the mean number of cigarettes smoked was 18 The standard deviation of the sample was 6 At 0 05 is the number of cigarettes a person smokes per day in this study significantly different from 14 24 points a State the question ID the population b State the null and alternative hypotheses define symbols c Analyze your data statistically d What is the critical value that you will use to compare to your statistic e Provide a statement of conclusion that includes statistical evidence and makes inference back to the population 27 100 couples used methods to increase the chance of having a girl baby 65 of the 100 couples had girls Is this result significantly greater than the 48 US Average for girl births Assume 0 05 24 points a State the question ID the population b State the null and alternative hypotheses define symbols c Analyze your data statistically d What is