Self-Quiz Unit 3 - Selection of my best coursework PDF

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Selection of my best coursework...

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SELF QUIZ UNIT 3 Introduction to Statistics Question 1 In Figure A you will find box plots for three sets of data. In Figure B are the histograms for the same sets of data, but in a different order. Associate each box plot with its relative histogram. Figure A:

Figure B:

Box plot 1 b Box plot 2 a Box plot 3 c Feedback Observe the range of distribution each data: [10,40] in Histogram a, [-40,30] in Histogram b and [14,28] in Histogram c. (You may want to increase the Plot. That can be done on many browsers with Control plus the "+" key. Or you may download the figure an open it with a graphical application.) The correct answer is: Box plot 1 → Histogram b, Box plot 2 → Histogram a, Box plot 3 →Histogram c Question 2 Consider the box plots in Figure A. Which of the data has a smaller inter-quartile range (IQR)? Figure A a. Box plot 1 b. Box plot 2 c. Box plot 3 d. Cannot tell based on the box plots. Feedback The height of the central box in Box-plot 3 is the least of the three. The correct answer is: Box plot 3 Information For the next 3 question deal with the following data: 11.9, 11.0, 12.4, 16.9, 16.3, 13.3, 9.1, 17.0, 11.0, 9.3, 25.3, 17.4, 17.4 Question 3 The median is equal to: a. 9.1 b. 13.3 c. 14.8 d. Cannot tell based on the given information. Feedback Run the code: > x median(x) [1] 13.3 The correct answer is: 13.3

Question 4 The largest value in the data is an outlier: a. True b. False c. Cannot tell based on the given information. Feedback Run the code: > x < -c(11.9,11.0,12.4,16.9,16.3,13.3,9.1, 17.0,11.0, 9.3,25.3,17.4,17.4) > boxplot(x) Observe, in the box plot that is created, that there are no outliers. The correct answer is: False Question 5 The smallest value in the data is an outlier: a. True b. False c. Cannot tell based on the given information. Feedback Run the code: > x boxplot(x) Observe, in the box plot that is created, that there are no outliers. The correct answer is: False Question 6 Create an R data frame with the name "ex.2" that contains the data in the file "ex2.csv" (Select the file name to download it). Compute the standard deviation of each of the numeric variables. Among the following, the variable with the largest standard deviation is: a. age b. bmi c. systolic d. diastolic Feedback After saving the file in the working directory run the code: > ex.2 sd(ex.2$age) [1] 3.805571 > sd(ex.2$bmi) [1] 3.881489 > sd(ex.2$systolic) [1] 11.27262 > sd(ex.2$diastolic) [1] 11.56522 The correct answer is: diastolic

Information Twenty-one randomly selected students were asked the number of pairs of sneakers they owned. The number of pairs of sneakers owned by each student was recorded in an R object by the name "x". The frequency table of the data "x" is: > table(x) x 1 2 3 4 5 6 4 7 3 3 2 2 Based on this table compute: Question 7 The sample mean ( ) is 2.904762 Feedback Run the code: > x.val freq rel.freq x.bar x.bar [1] 2.904762 The correct answer is: 2.904762 Question 8 The sample standard deviation (s) is 1.609496 Feedback Run the code: > x.val freq rel.freq x.bar var.x sqrt(var.x) [1] 1.609496 The correct answer is: 1.609496 Question 9 The first quartile (Q1) is 2 Feedback Run the code: > x.val freq rel.freq data.frame(x.val,cumsum(rel.freq)) x.val cumsum.rel.freq.

1 1 0.1904762 2 2 0.5238095 3 3 0.6666667 4 4 0.8095238 5 5 0.9047619 6 6 1.0000000 Observe that more than 25% of the distribution has accumulated at value "2" but less than that at value "1". The correct answer is: 2 Question 10 The median is 2 Feedback Run the code: > x.val freq rel.freq data.frame(x.val,cumsum(rel.freq)) x.val cumsum.rel.freq. 1 1 0.1904762 2 2 0.5238095 3 3 0.6666667 4 4 0.8095238 5 5 0.9047619 6 6 1.0000000 Observe that more than 50% of the distribution has accumulated at value "2" but less than that at value "1". The correct answer is: 2 Question 11 The third quartile (Q3) is 4 Feedback Run the code: > x.val freq rel.freq data.frame(x.val,cumsum(rel.freq)) x.val cumsum.rel.freq. 1 1 0.1904762 2 2 0.5238095 3 3 0.6666667 4 4 0.8095238 5 5 0.9047619 6 6 1.0000000 Observe that more than 75% of the distribution has accumulated at value "4" but less than that at value "3". The correct answer is: 4 Question 12 The distribution is skewed to the left? (True or False) False Feedback Observe that the frequency of the values "1" and "2" is more than the frequency of the values "5" and "6". The correct answer is: False Question 13 The relative frequency of the students that owned more than one but less than 5 sneakers is is 0.6190476

Feedback Compute: (7+3+3)/(4+7+3+3+2+2) = 0.6190476 The correct answer is: 0.6190476 Information Following are the possible weights (in pounds) of some football team members. 232, 251, 257, 268, 238, 222, 265, 263, 252, 246, 253, 248, 256, 248, 230, 219, 224, 267, 259, 254, 254, 261, 248, 221, 252, 269, 269, 273, 273, 259, 251, 222, 248, 224 Question 14 The sample mean ( ) is 249.2941 Feedback Run the code: > x mean(x) [1] 249.2941 The correct answer is: 249.2941 Question 15 The sample standard deviation (s) is 16.34019 Feedback Run the code: > x sd(x) [1] 16.34019 The correct answer is: 16.34019 Question 16 The first quartile (Q1) is 240 Feedback Run the code: > x summary(x) Min. 1st Qu. Median Mean 3rd Qu. Max. 219.0 240.0 252.0 249.3 260.5 273.0 The correct answer is: 240 Question 17

The median is 252 Feedback Run the code: > x summary(x) Min. 1st Qu. Median Mean 3rd Qu. Max. 219.0 240.0 252.0 249.3 260.5 273.0 The correct answer is: 252 Question 18 The third quartile (Q3) is 260.5 Feedback Run the code: > x summary(x) Min. 1st Qu. Median Mean 3rd Qu. Max. 219.0 240.0 252.0 249.3 260.5 273.0 The correct answer is: 260.5 Question 19 The USC quarterback Matt Barkley weighed 220 pounds in the spring of 2010. How many standard deviations above or below the mean was he in comparison to the data given above? (Give the answer in the format x.xxx, without the plus/minus sign) 1.792765 Feedback Observe that: (220 - 249.294)/16.340 = -1.792778 The correct answer is: 1.792765 Question 20 The following frequency table shows the lengths of 42 international phone calls using a $5 prepaid calling card. The data was stored in an object by the name "x": x 4 14 24 34 44 54 2 6 13 13 6 2 Using the data, and without computing the mean and the median, determine which ONE of the answers is correct: a. The mean and the median are equal. b. The mean is smaller than the median. c. The mean is larger than the median.

Feedback Observe that the distribution is symmetric. The values are equally spaced and the frequencies evenly distibuted. The correct answer is: The mean and the median are equal. Question 21 Consider the following data set: 4, 6, 6, 12, 18, 18, 18, 200. What value is (approximately) 0.75 standard deviations below the mean? a. There is not enough information b. Approximately -15 c. Approximately 4 d. Approximately 34.5 Feedback Consider the code: > x mean(x) - 0.75*sd(x) [1] -14.87231 The correct answer is: Approximately -15...