MATH 1280 Self - Quiz Unit 2– University of the People| MATH1280 Self - Quiz Version 2– ( Graded A)

MATH 1280 Self - Quiz Unit 2– University of the People Information text 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. Frequency of Hurricane Direct Hits Category # Direct Hits Relative Freq. Cum. Relative Freq. 1 0.39930 0.3993 2 72 3 0.2601 4 0.0659 5 0.0110 1.0000 Question 1 Correct Question text What is the relative frequency of direct hits that were category 2 hurricanes? Select one: 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 Incorrect Question text The relative frequency of direct hits that were AT LEAST a category 3 storm is Answer 0.337 . (The numerical answer that you provide should be of the form "", 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 text 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 Freq. Relative Freq. Cum. Relative Freq. 0 27 0.4500 1 18 3 0.9333 6 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 "", with 4 digits to the right of the zero.) Question 3 Correct Question text The relative frequency that flossed 6 times per week is: Answer: 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 Correct Question text The relative frequency that flossed at least once a week is: Answer: 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 text 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 Correct Question text The sample size is: Select one: 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 Correct Question text The frequency of production series where there are 4 malfunctioning products is: Select one: 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 Correct Question text 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 text The file "" contains information on the blood pressure of a group of healthy individuals. The file is located in Question 8 Correct The number of variables is: Answer: 7 Feedback: After saving the file "" in the working directory one can use the code ex2 - ("") in order to read the file into a data frame by the name "ex2". Writing the content of the object to the screen will produce: ex2 id sex age bmi systolic diastolic group 1 FEMALE 34 28..5887 64.84949 NORMAL 2 FEMALE 33 18..9261 78.71555 NORMAL 3 MALE 32 27..3985 86.57248 NORMAL ... The correct answer is: 7 Question 9 Correct Question text The type of the variable "id" is: Select one: 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: numeric Question 10 Correct Question text The type of the variable "sex" is: Select one: a. numeric b. factor Feedback: Values are non-numeric: "MALE" and "FEMALE". The correct answer is: factor Question 11 Correct Question text The type of the variable "diastolic" is: Select one: a. numeric b. factor Feedback: All values are numeric. The correct answer is: numeric Information text 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 Correct Question text "Age" is what type of data? Select one: a. qualitative/factor b. quantitative/numeric Feedback: Age is a numeric measurement. The correct answer is: quantitative/numeric Question 13 Correct Question text "Type of activity" is what type of data? Select one: a. qualitative/factor b. quantitative/numeric Feedback: This variable obtains categorical values The correct answer is: qualitative/factor Identify the type of data that would be used to describe a response for each of the items below: Question 14 Correct Number of tickets sold to a concert. Select one: a. qualitative/factor b. quantitative/numeric Feedback: The correct answer is: quantitative/numeric Question 15 Correct Favorite baseball team. Select one: a. qualitative/factor b. quantitative/numeric Feedback: The correct answer is: qualitative/factor Question 16 Correct Number of students enrolled at Evergreen Valley College. Select one: a. qualitative/factor b. quantitative/numeric Feedback: The correct answer is: quantitative/numeric Question 17 Correct Distance to the closest movie theater. Select one: a. qualitative/factor b. quantitative/numeric Feedback: The correct answer is: quantitative/numeric Question 18 Correct Number of competing computer spreadsheet software packages. Select one: a. qualitative/factor b. quantitative/numeric Feedback: The correct answer is: quantitative/numeric