MATH 1280: Introduction to Statistics/ Qs with
Certified Ans/ 2024-2025
An automobile producing company operates car dealerships that sell its cars. In order to assess
the service customers, get at the dealerships, a team from the Customer Relationship
Department was assembled. The team was sent to 20 randomly selected dealerships. Each
dealership was visited once by the team for an entire working day. During a visit, the team
interviewed all the customers that arrived at that dealership.
One of the questions that each of the customers was asked is: "Do you currently possess a car
made by our company?" The answers were marked down as "Yes", "No", or "Refuse to Answer",
depending on the customer's response.
Select the correct answer in each of the following 4 questions: - Answer: The population in this
survey is:
B) Customers that arrive at dealerships of the company.
Page 1 of 10
, 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.
Compute the standard deviation of each of the numeric variables. Among the following, the
variable with the largest standard deviation is: - Answer: a. age
b. bmi
c. systolic
D. DIASTOLIC
After saving the file in the working directory run the code:> ex.2 <- read.csv("ex2.csv")>
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
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:
The sample mean () is: - Answer: Answer is: 2.904762
Run the code: > x.val <- c(1,2,3,4,5,6) > freq <- c(4,7,3,3,2,2) > rel.freq <- freq/sum(freq) > x.bar
<- sum(x.val*rel.freq) > x.bar [1] 2.904762
The sample standard deviation (s) is: - Answer: Answer is: 1.609496
Run the code: > x.val <- c(1,2,3,4,5,6) > freq <- c(4,7,3,3,2,2) > rel.freq <- freq/sum(freq) > x.bar
<- sum(x.val*rel.freq) > var.x <- sum((x.val-x.bar)^2*freq)/(sum(freq)-1) > sqrt(var.x) [1]
1.609496
Page 2 of 10
Certified Ans/ 2024-2025
An automobile producing company operates car dealerships that sell its cars. In order to assess
the service customers, get at the dealerships, a team from the Customer Relationship
Department was assembled. The team was sent to 20 randomly selected dealerships. Each
dealership was visited once by the team for an entire working day. During a visit, the team
interviewed all the customers that arrived at that dealership.
One of the questions that each of the customers was asked is: "Do you currently possess a car
made by our company?" The answers were marked down as "Yes", "No", or "Refuse to Answer",
depending on the customer's response.
Select the correct answer in each of the following 4 questions: - Answer: The population in this
survey is:
B) Customers that arrive at dealerships of the company.
Page 1 of 10
, 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.
Compute the standard deviation of each of the numeric variables. Among the following, the
variable with the largest standard deviation is: - Answer: a. age
b. bmi
c. systolic
D. DIASTOLIC
After saving the file in the working directory run the code:> ex.2 <- read.csv("ex2.csv")>
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
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:
The sample mean () is: - Answer: Answer is: 2.904762
Run the code: > x.val <- c(1,2,3,4,5,6) > freq <- c(4,7,3,3,2,2) > rel.freq <- freq/sum(freq) > x.bar
<- sum(x.val*rel.freq) > x.bar [1] 2.904762
The sample standard deviation (s) is: - Answer: Answer is: 1.609496
Run the code: > x.val <- c(1,2,3,4,5,6) > freq <- c(4,7,3,3,2,2) > rel.freq <- freq/sum(freq) > x.bar
<- sum(x.val*rel.freq) > var.x <- sum((x.val-x.bar)^2*freq)/(sum(freq)-1) > sqrt(var.x) [1]
1.609496
Page 2 of 10
