R MCQs (Chapterwise Multiple Choice Questions)

What is the output of the following R code? x<-2; y <- c(1:3); paste("The value of x is", x, "and the value of y[x] is", y[x], sep=" ")

"The value of x is 2 and the value of y[x] is c(1:3)[2]"

"The value of x is 2 and the value of y[x] is 4"

"The value of x is 2 and the value of y[x] is 2"

"The value of x is 2 and the value of y[x] is 6"

Answer & Explanation

Correct Answer: "The value of x is 2 and the value of y[x] is 2"

Note: This Question is unanswered, help us to find answer for this one

Let X be a 3x4 matrix with non-zero values. The result of: > apply(X, 2, mean), is:

equal to the result of: >c(mean(X[,1]), mean(X[,2]), mean(X[,3]))

equal to the result of: >c(mean(X[1,]), mean(X[2,]), mean(X[3,]), mean(X[4,]))

equal to the result of: >c(mean(X[,1]), mean(X[,2]), mean(X[,3]), mean(X[,4]))

equal to the result of: >c(mean(X[1,]), mean(X[2,]), mean(X[3,]))

Answer & Explanation

Correct Answer: equal to the result of: >c(mean(X[,1]), mean(X[,2]), mean(X[,3]), mean(X[,4]))

Note: This Question is unanswered, help us to find answer for this one

Which will test the hypothesis that two independent Normally distributed random variables A and B have different means?

t.test( A, B, paired = TRUE )

mean( A ) == mean( B )

ks.test( A, B )

t.test( A, B, paired = FALSE )

Answer & Explanation

Correct Answer: t.test( A, B, paired = FALSE )

Note: This Question is unanswered, help us to find answer for this one

Which is INCORRECT regarding the command: T <- 40; rnorm( T, 1, 4) ?

it draws 1 number from 40 different Normal distributions

it draws 40 pseudo-random numbers

it draws 40 random numbers from a Normal distribution with mean of 1

it draws 40 random numbers from a Normal distribution with standard deviation of 4

Answer & Explanation

Correct Answer: it draws 1 number from 40 different Normal distributions

Note: This Question is unanswered, help us to find answer for this one

Which R function provides basic descriptive summary statistics for a numeric vector x?

summarize x

summary(x)

proc contents x;

summarize(x)

Answer & Explanation

Correct Answer: summary(x)

Note: This Question is unanswered, help us to find answer for this one

What is the output for the command: > rep( c(1:2), each = 3)

[1] 1 1 1 2 2 2

[1] 1 2 1 2 1 2

[1] "1:2" "1:2" "1:2"

[1] 3 6

Answer & Explanation

Correct Answer: [1] 1 1 1 2 2 2

Note: This Question is unanswered, help us to find answer for this one

What does the following R code output? Y <- c(1,2,3); X <- rep(c(1,length(Y)), times=2); X

1 2 1 2

1 1

1 1 3 3

1 3 1 3

Answer & Explanation

Correct Answer: 1 3 1 3

Note: This Question is unanswered, help us to find answer for this one

How are these data types alike: logical, integer, numeric, and character?

Each is a type of data frame.

Each is a type of atomic vector.

Each is a type of complex vector.

Each is a type of raw vector.

Answer & Explanation

Correct Answer: Each is a type of atomic vector.

Note: This Question is unanswered, help us to find answer for this one

How do you extract the values above the main diagonal from a square matrix named Rmat?

Rmat[upper.tri(Rmat)]

Upper.triangular(Rmat)

Upper.tri(Rmat)

Upper.diag(Rmat)

Answer & Explanation

Correct Answer: Rmat[upper.tri(Rmat)]

Note: This Question is unanswered, help us to find answer for this one

What is the output of: rrr <- 5.45667; sprintf("%1.f", round(rrr, 3))

5

"5"

5.457

5.5

Answer & Explanation

Correct Answer: "5"

Note: This Question is unanswered, help us to find answer for this one

R Quick Quiz

Poor Results!

You need a lot of improvement.

Just don't give up!

Correct Answers: 0/10

Start Practicing with our MCQs given below.