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9/12/2018 Self-Quiz Unit 1MATH 1281 Statistical Inference - Term 1, 2018-2019
Home ► My courses ► MATH 1281 - AY2019-T1 ► 6 September - 12 September ►
Self-Quiz Unit 1
Started on Wednesday, 12 September 2018, 11:34 PM
State Finished
Completed on Wednesday, 12 September 2018, 11:35 PM
Time taken 1 min 7 secs
Grade 10.00 out of 10.00 (100%)
Information
The data set "cars.csv" was introduced in Chapter 9 of the book. This data
set contains information on various models of cars. Download this le to
your computer and store it in the working directory of R. The le can be
downloaded from MATH 1281 Data Files in the course page for MATH
m
1281.
er as
co
The variable "width" in the data set contains the width of the body of the
eH w
car in inches. The variable "length" contains the length of the body of the
o.
car in inches. Produce a new variable by the name "area" that contains the
rs e
area of the body of the car. This variable should be produced by
ou urc
multiplying the the width of the body by the length of the body. Answer the
following questions with respect to the variable "area":
o
aC s
vi y re
Question 1 The variable "area" is a:
ed d
Correct
ar stu
Mark 1.00 out of Select one:
1.00 a. Numeric
is
b. Factor
Th
Upload the le "cars.csv" to a data set by the name "cars" using the code:
sh
cars <- read.csv("cars.csv") . Form the variable "area" using the code:
area <- cars$length*cars$width . The variable "area" is a product of two
numeric variables and it obtains numeric values as well.
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, 9/12/2018 Self-Quiz Unit 1
Question 2 The average area of the body of a car is:
Correct
Mark 1.00 out of Answer: 11493.36
1.00
Apply the code: mean(area) . The sample average turn out to be equal to
11493.36. Alternatively, you may apply the code: summary(area) and obtain
the value of the mean from the produced report.
Question 3 The median area of the body of a car is:
Correct
Answer: 11314.2
m
Mark 1.00 out of
er as
1.00
co
eH w
o.
rs e
ou urc
Apply the code: median(area) . The sample median turn out to be equal to
11314.2. Alternatively, you may apply the code: summary(area) and obtain
the value of the median from the produced report.
o
aC s
vi y re
Question 4 The interquartile range of the area is:
Correct
ed d
Answer: 1566.18
ar stu
Mark 1.00 out of
1.00
is
Th
Apply the code: quantile(area,c(0.25,0.75)) . The rst quartile (Q1) is equal to
10709.72 and the third quartile (Q3) is equal to 12275.90. The di erence
sh
between Q3 and Q1 is the interquartile range and is equal to IQR = Q3 - Q1
= 1566.18.
Alternatively, you may apply the code: summary(area) and obtain the values
of Q1 and Q3 from the produced report.
This study source was downloaded by 100000818637348 from CourseHero.com on 04-13-2021 16:47:18 GMT -05:00
https://my.uopeople.edu/mod/quiz/review.php?attempt=1385473 2/6
https://www.coursehero.com/file/53098002/Self-Quiz-Unit-1-anspdf/
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