Statistics 201 Exam 1 from Fall 2013 Practice Exam 1 for Spring 2014 This practice exam is provided solely for the purpose of familiarizing you with the format and style of the Stat 201 exams There is no explicit or implicit guarantee that the upcoming exam will ask similar questions If you use the practice exam as your only tool to help you prepare for the upcoming exam you most likely will not do well on the exam You should still do the things you would have done if you did not have access to this practice exam such as re read the text go over your class notes re work the online homework problems and look at the list of exam topics provided and make sure that you understand all the concepts listed within it 1 1 A study at a medical center examined 129 people to see if contracting hepatitis C was associated with having diabetes Researchers used medical records to determine whether or not the subject has diabetes and or hepatitis C Report your answers to TWO decimal places HAS hepatitis C Does NOT have hepatitis C Total HAS diabetes 21 39 Does NOT have diabetes 12 57 Total 60 69 129 33 96 i 3 points What percent of the subjects do not have hepatitis C ii 3 points What percent of the subjects who have diabetes do not have hepatitis C iii 3 points What percent of the subjects with hepatitis C do not have diabetes iv 4 points Do you think there is an association between hepatitis C virus and diabetes Circle your answer YES NO Using the mosaic plot below briefly explain your answer in the space to the right of the plot 2 2 5 points The response times of a particular web server are approximately normally distributed with a mean of 120 milliseconds and a standard deviation of 15 milliseconds Given that any value from a normal distribution with a z score of 0 841 represents the 20th percentile use this fact to calculate the 80th percentile for these response times 3 5 points Suppose that the wait time to reach a technical support person at a large software company is approximately normally distributed with a mean of 4 minutes and a standard deviation of 0 5 minutes Approximately what percent of customers will wait less than 2 75 minutes Use one of the screenshots on the next page to help you answer this question Show any work below and write your final answer on the blank line below Report your final answer to 4 decimal places Final Answer is 3 Problem 3 continued 4 4 A survey of college freshmen asked how many minutes per day they talk on the phone The box plots below display the data for female and male students Answer the questions below based on what you see in the image i 3 points Which of the following statements is true circle the best answer a The median number of minutes spent on the phone by males is higher than the median number of minutes for females b The minimum number of minutes is lower for males than the minimum for females c Females have the greatest IQR d None of the statements are true ii 3 points The group that seems to have the most outliers is circle the best answer a males b females c none of the groups appear to have outliers d cannot be determined from box plots iii 3 points The group with the least amount of overall variation is circle the best answer a males b females c the groups appear to be similar in terms of overall variation d cannot be determined from box plots 5 5 The following data are from a Sporting Goods Company that manufactures and sells products This small subset of the company s employee data is from its human resource department Employee Abram Doug Baker Baker Baker Christine Johnson Paul Parker Laura Edwards John Deal Karl Smith Smith Wood Janice Bunch Chris Morris Bradley i Department Sales Production Administration Production Production Maintenance Administration Maintenance Sales Sales Administration salary 35000 41000 29000 49000 65000 30000 32000 32000 38000 41000 35000 years employed 2 1 1 5 8 2 4 2 2 3 6 Vacation days 8 0 6 5 12 0 8 0 0 5 15 Vision insuance Yes or No Y Y Y N Y Y Y N N Y Y Location Boston Chicago Boston Nashville Boston Boston Nashville Nashville Chicago Nashville Chicago 401k contibution amount 2 3 1 3 5 0 3 0 0 4 5 4 points Indicate whether the variables are quantitative Q categorical C or identifier I in the space above the column headings Label each column as only ONE type of variable ii 2 points Name two variables listed above that one could use to create a scatter plot ii 2 points Name another CATEGORICAL variable that could be added to this table regarding employee data 6 6 The pivot chart below displays average high school GPA by family income and gender from a sample of Stat 201 students from Spring Semester 2013 i 3 points Which of the following statements are false CIRCLE only ONE answer a Females have higher average GPAs than males across all family income levels b Males from the middle class family income level have the highest GPAs compared to males from the other income categories c Females from the lower class family income level have drastically different GPAs on average than females from upper class family income level d Males from lower class family income have the lowest overall average GPAs than all other income levels and gender classifications e None of the income by gender classifications have average GPAs lower than 3 10 ii 3 points In one complete sentence suggest something to improve the quality of the Pivot Chart above There are several possible correct responses 7 7 The following stem and leaf and histogram display shows the populations of residents in millions of people according to the 2010 census in all 50 states in the U S Use the graphical displays along with the given 5 number summary to answer the following questions below Stem and Leaf Histogram Min 0 1 25th Percentile 0 2 50th Percentile 0 45 75th Percentile 0 725 Max 3 7 i 2 points Report the mode s of this data set if it they exist s If no mode exists write no mode ii 3 points Without doing any calculations which summary statistic must be larger the mean or the median Why Briefly justify how you know this iii 3 points Using either graphical display describe the shape of the distribution along with any unusual features 8 Problem 7 continued iv 3 points Approximately 75 of the states have populations of citizens below what value v 2 points Calculate the range of the middle 50 of the populations of residents of the United States in millions of people vi 2 points What is the bin width of the histogram on the previous page 8 3
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