STAT 200 QUIZ 1 Name: _______________ Summer 2016 Dr. Thengumthara I have completed this assignment myself, working independently and not consulting anyone except the instructor. Signature: _____________________ INSTRUCTIONS The quiz is worth 60 points. The quiz covers Week 1 and Week 2 materials. Make sure your answers are as complete as possible and show your work/argument. When there are calculations involved, you should show how you come up with your answers with critical work and/or necessary tables. You must show/ explain why you choose certain answer multiple choice questions. The quiz is open book and open notes. This means that you may refer to your textbook, notes, and online course materials, but you must work independently and may not consult anyone. The brief honor statement is on top of the exam. If you fail to put your name under the statement, your quiz will not be accepted. You may take as much time as you wish, provided you turn in your quiz via LEO by 11:59 pm EDT on Sunday, July 9. For Questions 1 to 10: Choose the correct answer. (2 points each) 1. In an experiment on the effect of sleep on memory, the independent variable is __ a. Number of hours of sleep b. Recall score on a memory test c. Gender of the subjects d. Gender of the experimenter 2. A right-skewed distribution is also called a __ distribution. a. Positively-skewed b. Negatively-skewed c. Kurtosis d. Normal 3. A prospective graduate student may be interested in gender balance at the university s/he will attend. Data on how many males and females attend the institution are examples of: a. Descriptive statistics b. Inferential statistics 4. In an experiment on the effect of exercise on memory, the independent variable is __(choose only one answer) a. Number of hours of exercise b. Recall score on a memory test c. Gender of the subjects d. Gender of the experimenter 5. Linear Transformations involve: a. Multiplication of a variable by a constant b. Square roots c. Logarithms 6. Stratified sampling___ a. Can be more representative than simple randomized sampling b. Can be used if the population has a number of distinct groups c. Is done by randomly sampling from subgroups in a way that is proportional to their size in the population d. All of the above 7. For the following box plot, E represents: a. The upper hinge b. The median c. The mean d. A far out value 8. A right-skewed distribution is also called a __ distribution. a. Positively-skewed b. Negatively-skewed c. Kurtosis d. Normal 9. Stratified sampling___ a. Can be more representative than simple randomized sampling b. Can be used if the population has a number of distinct groups c. Is done by randomly sampling from subgroups in a way that is proportional to their size in the population d. All of the above 10. \"Duration (amount of time)\" is what type of data? a. qualitative b. quantitative discrete c. quantitative continuous 11. (Show all work, 6 points) Average temperature on April 14th for the 16, years ending in 2010 for the city Des Moines, Iowa is given below (www.weather.com). Find the maximum, minimum, mean, median temperature on April 14th for this city. 56, 37.5, 37.2, 56, 54.3, 63.3, 54.7, 60.6, 70.6, 53.7, 52.9, 74.9, 44.4, 40.3, 44.4, 71 Maximum: Minimum: Mean: Median: 12. (Show all work, 6 points) Quiz score for students in a Statistics class are given below. Find the Inter Quartile Range. 98, 85,89,73,76,85,87,92,85,56 a. What percentage of the survey answered "not sure"? b. What percentage think that middle-class is from $25,000 to $50,000? c. Construct a histogram of the data. i. Should all bars have the same width, based on the data? Why or why not? ii. How should the <20,000 and the 100,000+ intervals be handled? Why? d. Find the 40th and 80th percentiles e. Construct a bar graph of the data 13.(6 points) Use the box plot below to answer the questions below: 84. Given the following box plot: Figure 2.41 a. b. c. d. e. quarter the smallest spread which quarter(a) has which the smallest spreadhas of data? What is that spread?of data? What is that spread? which quarter has the largest spread of data? What is that spread? find the interquartile range (IQR). are there more data in the interval 5-10 or in the interval 10-13? How do you know this? which interval has the fewest data in it? How do you know this? i. 0-2 ii. 2-4 iii. 10-12 (b) Are there more data in the interval 5-10 or in the interval 10-13? How iv. 12-13 this? v. need more information do you know 85. The following box plot shows the U.S. population for 1990, the latest available year. 14. (6 points, show all work) The table contains data on hurricanes that have made direct hits on the U.S. between 1851 and 2004. A hurricane is given a strength category rating based on the minimum wind speed generated by the storm. Figure 2.42 (a)fewer Complete the table the answers 4 decimal a. Are there or more children (age(Round 17 and under) than seniorto citizens (age 65places) and over)? How do you know? b. 12.6% are age 65 and over. Approximately what percentage of the population are working age adults (above age 17 to age Category 65)? Number of Relative Cumulative Direct Hits Frequency Frequency 1 92 86. In a survey of220-year-olds 81 in China, Germany, and the United States, people countries they had visited in their lifetime. The following box plots display the results. 3 76 4 12 5 3 Total = 2.4 Box Plots were asked the number of foreign (b) What is the percentage of direct hits that were AT MOST a category 2? 15. (6points) The number of service upgrades sold by each of 10 employees is as follows: 6, 21, 10, 8, 11, 14, 20,16, 15, 18. However, when the data was entered into the statistical program, the score that was supposed to be 12 was entered as 21. You had calculated the following measures of central tendency: the mean, the median, and the mean trimmed 25%. Which of these measures of central tendency will change when you correct the recording error? Justify your answer. 16. (10 points) Low-density lipoprotein (LDL) is an important part of blood cholesterol test. To prevent cardiovascular disease, a health center had a free blood cholesterol test for all the people older than 65 in the community. A total of eight people attended the blood screening and their blood test results are listed below. What is the standard deviation of the LDL levels (mg/dL) in the sample? Show your intermediate calculation in the following table; you may not need all columns based on the formula you use. Round the answer to two decimal places as needed. LDL(mg/dl): 130,143,114,110,123,110,134,124 LDL x Sum x2 x - mean (x - mean)2 \f\f