l3-> E e r' d 3 s g Q V . ' Introductory Statistics Third Edition Perdisco ookmark AEEEEDJEHE ....................................................................................................................................................................................................................................................................................................................................... Below is a set of assessable homework questions on this topic, selected by your professor. Take care! Do not submit your answers until you have read all the instructions and answered the questions carefully. When you submit your answers, you will receive immediate feedback. Navigating this page: Submit answers: Submit your answers for immediate grading Bookmark: Save this question set so that you can come back to it later El 1 of 2 ID: MST.FET.E.PE.01.0010A A 91% confidence interval for the mean has been calculated using a sample size of 20. If the sample size is increased then, all other things remaining constant, the confidence interval will become . El 2 of 2 ID: MST.FET.E.PE.02.0020A All statistical estimates inherently involve some level of imprecision and some level of uncertainty. Beth has collected a sample from a numerical variable X. She has calculated a sample mean of 6,164. From this, Beth draws the following inference: 'The population mean of X is somewhere between 6,114 and 6,214. ' In this inference, Beth has: acknowledged the imprecision but failed to acknowledge the uncertainty in statistical estimates failed to acknowledge both the imprecision and uncertainty in statistical estimates acknowledged both the imprecision and the uncertainty in statistical estimates GOOD acknowledged the uncertainty but failed to acknowledge the imprecision in statistical estimates Perdisco / latin /, v., to learn thoroughly @ 2010 Perdisco E e r- d J s C Q Terms Of Use I Privacy Policy I Wednesday, November 30, 2016, 10211 http://www.perdisco.com.au% Top LSAT Prep Bc >< Steven Universel X G roscoes menu-G B https://www.perd X ' l3-> https://www.perdisco.oom/elms/qsam/html/qsam.aspx <- (3' Below is a set of assessable homework questions on this topic, selected by your professor. Take care! Do not submit your answers until you have read all the instructions and answered the questions carefully. When you submit your answers, you will receive immediate feedback. Navigating this page: Submit answers: Submit your answers for immediate grading Bookmark: Save this question set so that you can come back to it later El 1 of 3 ID: MST.FET.E.CIMSU.01.0010A [4 marks] Internet company Gurgle is carrying out testing on the efficiency of its search engine. A sample of 60 searches have been carried out and the time taken to display the results has been recorded for each search. The mean search time for the sample was < l calculated as 0.1420 seconds. The standard deviation of the search times for the sample was calculated as 0.0160 seconds. The C population standard deviation of search times is unknown. a) Select all the techniques that are commonly used to construct a confidence interval for the mean when the population standard deviation (0) is unknown: O Approximate the population standard deviation (0) with the sample standard deviation (5) 0 Replace the sample size (n) with n-1 O Decrease the confidence level to compensate for the increased margin of error 0 Approximate the standard normal distribution with the Student's t distribution b) Calculate the upper and lower bounds of the 95% confidence interval for the mean search time for the Gurgle search engine. You may find this Student's t distribution table useful. Give your answers in seconds to 4 decimal places. Upper bound = G seconds Lower bound = [3 seconds El 2 of 3 ID: MST.FET.E.CIMSU.02.004OA A newspaper runs a competition each week. To enter this competition, readers must correctly complete the weekly crossword puzzle and send it in to the paper, along with a proof of purchase. All such entries go into a weekly draw for a prize. The newspaper would like to estimate the average number of entries each week. A random sample of 31 weeks are chosen, and it is observed that the average number of entries over these weeks is 807.3. The sample standard deviation is 36.9. Calculate the 95% confidence interval for the mean number of entries in the newspaper competition. You may find this Student's t distribution table useful. Give your answers to 2 decimal places. El 3 of 3 ID: MST.FET.E.CIMSU.03.0010A Tyler and Jack are both studying a numerical variable X. Both students want to estimate the population mean of this variable, and they each intend to collect a sample, calculate a sample mean and construct a 95% confidence interval. Each student will collect their own sample, but both samples will have 30 items in them. When constructing his confidence interval, Tyler assumes a value for the population standard deviation, 0. In contrast, Jack does not assume a value for the population standard deviation. Jack calculates the sample standard deviation, 5, and uses this in his confidence interval. However as it turns out, the sample standard deviation that Jack calculates turns out to be equal to the value assumed by Tyler for the population standard deviation. Based on this information, it is true to say that: O Tyler's confidence interval will be wider than Jack's O Jack's confidence interval will be wider than Tyler's 0 it is impossible to tell which confidence interval will be wider 0 both confidence intervals will be of the same width Perdisco / latin /, v., to learn thoroughly @ 2010 Perdisco E e r- d J s c Q Terms Of Use l Privacy Policy I Wednesday, November 30, 2016, 10:13 http://www.perdisco.com.au% Top LSAT Prep Bc >< Steven Universel X G roscoes menu-G B https://www.perd X ' l3-> https://www.perdisco.oom/elms/qsam/html/qsam.aspx 'VVIICII YUU DUUIIIIL YUUI GIIDVVCI D, Yu" VVIII ICLCIVC IIIIIIICUICILC I'CCUUGLI'XE Navigating this page: Submit answers: Submit your answers for immediate grading Bookmark: Save this question set so that you can come back to it later El 1 of 3 ID: MST.FET.E.CIP.01.003OA [2 marks] A friend tells you that she has conducted a survey to find the proportion of people in her university that utilize the campus internet cafe at least once a day. She has collected a sample and calculated a sample proportion of p = 0.68. She uses this value to calculate a confidence interval for the population proportion. Your friend says that she is not going to tell you the sample size or the level of confidence used in her construction, but she does tell you that the upper bound for the interval is 0.83. From the following list, select the values that, based on the information given, could possibly be the lower bound of the confidence interval your friend calculated: [2 marks] El 2 of 3 ID: MST.FET.E.CIP.02.0030A A survey was run by a high school student in order to determine what proportion of mortgage-holders in his town expect to own their house within 10 years. He surveyed 134 mortgage holders and found that the proportion of these that did expect to own their house within 10 years is 0.65. The student decides to construct a 95% confidence interval for the population proportion. You may find this standard normal table useful for the following questions. a) Calculate the margin of error that the high school student will have. Give your answer as a decimal to 3 decimal places. Margin of error = C] A different high school student sees this survey and decides to try and repeat it. This second high school student also surveys 134 mortgage holders, and this student also finds that the proportion of these that do expect to own their house within 10 years is 0.65. However, this student wants to construct a 99% confidence interval for the population proportion. b) Calculate the margin of error that the second student will have. Give your answer as a decimal to 3 decimal places. Margin of error = C] E] 3 of 3 ID: MST.FET.E.CIP.03.0020A [3 marks] In a survey of 118 small business owners, a total of 84 of the owners had decided to downsize in the year following the Global Financial Crisis (GFC). a) Calculate the proportion of surveyed small business owners that downsized. Give your answer as a decimal to 2 decimal places. Sample proportion = C] A 95% confidence interval is to be constructed for the proportion of all small business owners that decide to downsize after the GFC. You may find this standard normal table useful for the following questions. If you use your answer to part a) in the following calculations, use the rounded version. b) Calculate the lower bound for the confidence interval. Give your answer as a decimal to 3 decimal places. Lower bound for confidence interval = G c) Calculate the upper bound for the confidence interval. Give your answer as a decimal to 3 decimal places. Upper bound for confidence interval = G Perdisco / latin /, v., to learn thoroughly @ 2010 Perdisco E e I" Ci I S m Terms Of Use I Privacy Policy I Wednesday, November 30, 2016, 10:14 http://www.perdisco.com.au