Self-Quiz Unit 2 - Selection of my best coursework PDF

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Selection of my best coursework...

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SELF QUIZ UNIT 2 Introduction to Statistics Information The next two questions refer to the following relative frequency table on hurricanes that have made direct hits on the U.S. between 1851 and 2004. Hurricanes are given a strength category rating based on the minimum wind speed generated by the storm. (http://www.nhc.noaa.gov/gifs/table5.gif) (ALTERNATE DOWNLOAD LINK) Frequency of Hurricane Direct Hits Category # Direct Hits 1 2 72 3 4 5

Relative Freq. Cum. Relative Freq. 0.39930 0.3993 0.2601 0.0659 0.0110

1.0000

Question 1 What is the relative frequency of direct hits that were category 2 hurricanes? a. 0.2637 b. 0.7363 c. 0.2601 d. Not enough information to calculate. Feedback The total of all relative frequencies is 1.000. Denote by p the relative frequency of category 2 hurricanes. Observe that 0.3993 + p + 0.2601 + 0.0659 + 0.0110 = 1.0000 Consequently, p = 1 - 0.3993 + 0.2601 + 0.0659 + 0.0110 = 1 - 0.7363 = 0.2637 The correct answer is: 0.2637 Question 2 The relative frequency of direct hits that were AT LEAST a category 3 storm is 0.337. (The numerical answer that you provide should be of the form "0.xxxx", with four digits to the right of the zero.) Feedback The relative frequency of category 3 or more is the sum of the relative frequencies of categories 3, 4 , and 5: 0.2601 + 0.0659 + 0.0110 = 0.3370 The correct answer is: 0.337

Information Sixty adults with gum disease were asked the number of times per week they used to floss before their diagnoses. The (incomplete) results are shown below: Flossing Frequency for Adults with Gum Disease # per Week 0 1 3 6

Freq. Relative Freq. Cum. Relative Freq. 27 0.4500 18 0.9333 3

7 1 0.0167 Fill in the blanks in the table and answer the next two question: (The numerical answer that you provide should be of the form "0.xxxx", with 4 digits to the right of the zero.) Question 3 The relative frequency that flossed 6 times per week is: 0.05 Feedback It is given that the total number of adults with gum disease is 60. There are 3 such adults that flossed 6 times per week. Therefore, the relative frequency is 3/60 = 0.0500 The correct answer is: 0.05 Question 4 The relative frequency that flossed at least once a week is: 0.55 Feedback The relative frequency of adults that do not floss at all is 0.4500. All other adults floss at least once a week. Their relative frequency is 1.0000 - 0.4500 = 0.5500. The correct answer is: 0.55 Information The number of malfunctioning products per production series was recorded for several production series. The data was entered into an R object by the name "malfunction". The next 3 questions refer to the following R code: Question 5 The sample size is: a. 8 b. 9 c. 72 d. Not enough information to tell.

Feedback The object "freq" contain the table of frequency of the production series, divided according to the number of malfunctioning products that they had. The cumulative frequency of all the production series that had 8 malfunctioning products or less, which includes all production series, is reported under the number "8" in the output of the expression "cumsum(freq)". This number is 72. The correct answer is: 72 Question 6 The frequency of production series where there are 4 malfunctioning products is: a. 57 b. 9 c. 16 d. Not enough information to calculate. Feedback The cumulative frequency of production series that have 4 malfunctioning products or less is 57. The cumulative frequency of production series that have 3 malfunctioning products or less or less is 41. The frequency of production series that have exactly 4 production series is the difference between these two numbers: 57 - 41 = 16. The correct answer is: 16 Question 7 The frequency of production series where there are less than 7 malfunctioning products is:Select one: a. 70 b. 71 c. 72 d. Not enough information to calculate. Feedback Having less that 7 malfunctioning products corresponds to having 6 malfunctioning products or less. The cumulative frequency of production series with 6 malfunctioning products or less is 70. The correct answer is: 70 Information The file "ex2.csv" contains information on the blood pressure of a group of healthy individuals. The file is located in http://pluto.huji.ac.il/~msby/StatThink/Datasets/ex2.csv. (ALTERNATE DOWNLOAD LINK) Read the data into R and answer the following 4 questions: Question 8 The number of variables is: 7 Feedback After saving the file "ex2.csv" in the working directory one can use the code > ex2 ex2 id sex age bmi systolic diastolic group 1 3695908 FEMALE 34 28.78903 112.5887 64.84949 NORMAL 2 5778095 FEMALE 33 18.91321 122.9261 78.71555 NORMAL 3 5138370 MALE 32 27.66339 128.3985 86.57248 NORMAL ... The correct answer is: 7 Question 9 The type of the variable "id" is: a. numeric b. factor Feedback All the values are numbers. Technically, R treats this variable as a numeric sequence. However, one would typically not use this variable for statistical inference. Usually, it serves as a key, a unique identifier, in data set management. The correct answer is: factor Question 10 The type of the variable "sex" is: a. numeric b. factor Feedback Values are non-numeric: "MALE" and "FEMALE". The correct answer is: factor Question 11 The type of the variable "diastolic" is: a. numeric b. factor Feedback All values are numeric. The correct answer is: numeric Information A study was done to determine the age, type of activity, number of times per week and the duration (amount of time) of resident use of a local park in San Jose. The first house in the neighborhood around the park was selected randomly and then every 8th house in the neighborhood around the park was interviewed. Answer the following 2 questions:

Question 12 "Age" is what type of data? a. qualitative/factor b. quantitative/numeric Feedback Age is a numeric measurement. The correct answer is: quantitative/numeric Question 13 "Type of activity" is what type of data? a. qualitative/factor b. quantitative/numeric Feedback This variable obtains categorical values The correct answer is: qualitative/factor Information Identify the type of data that would be used to describe a response for each of the items below: Question 14 Number of tickets sold to a concert. a. qualitative/factor b. quantitative/numeric Feedback The correct answer is: quantitative/numeric Question 15 Favorite baseball team. a. qualitative/factor b. quantitative/numeric Feedback The correct answer is: qualitative/factor Question 16 Number of students enrolled at Evergreen Valley College. a. qualitative/factor b. quantitative/numeric Feedback The correct answer is: quantitative/numeric

Question 17 Distance to the closest movie theater. a. qualitative/factor b. quantitative/numeric Feedback The correct answer is: quantitative/numeric Question 18 Number of competing computer spreadsheet software packages. a. qualitative/factor b. quantitative/numeric Feedback The correct answer is: quantitative/numeric...