1. The arithmetic mean of all possible outcomes is known as
(A) expected value
(B) critical value
(C) variance
(D) standard deviation

Answer: A

Expectation (or expected value) is the arithmetic mean of all possible outcomes of a random variable.

2. Which of the following cannot be the value of a correlation coefficient?
(A) –1
(B) –0.75
(C) 0
(D) 1.2

Answer: D

The value of a correlation coefficient is always between –1 and 1, including –1 and 1.

3. Var (X) = ?
(A) E[X2] (B) E[X2] – E[X] (C) E[X2] + E[X]2
(D) E[X2] – E[X]2

Answer: D

By definition, Var (X) = E[X2] – E[X]2

4. Var (X + Y) = ?
(A) E[X/Y] + E[Y] (B) E[Y/X] + E[X] (C) Var(X) + Var(Y) + 2 Cov(X, Y)
(D) Var(X) + Var(Y) – 2 Cov(X, Y)

Answer: C

By definition, Var (X + Y) = Var(X) + Var(Y) + 2 Cov(X, Y)

5. What is the variance of the data set: 2, 10, 1, 9, and 3?
(A) 15.5
(B) 17.5
(C) 5.5
(D) 7.5

Answer: B

First, calculate the mean
Benue state civil service Past questions and answersNow calculate the variance,Benue state civil service Past questions and answers


1. Tunde and Tania went shopping, but __________ couldn’t find anything __________ liked.
(A) they, those
(B) they, them
(C) those, they
(D) they, they

The answer is: (D)

2. Nuclear energy is __________ dangerous to be used widely.
(A) so
(B) such
(C) too
(D) that

The answer is: (C)

3. If I have money, I __________ it tomorrow.
(A) will purchase
(B) would purchase
(C) have purchase
(D) have purchased

The answer is: (A)

4. Cannon had __________ unique qualities _________ it was used widely in ancient times.
(A) such, that
(B) such, so
(C) that, since
(D) that, that

The answer is: (A)


1. The oldest news agency in the world is

The answer is: (A)

2. AFP is a renowned news agency of which country?
(A) Switzerland
(B) France
(C) Germany
(D) Sweden

The answer is: (B)

3. How many electoral votes are required in the US presidential elections to become president of the United States?
(A) 250
(B) 270
(C) 350
(D) 370

The answer is: (B)

4. Currently, the largest economy in the world is the economy of
(A) China
(B) Russia
(C) Germany
(D) United States

The answer is: (D)

5. Which state of the United States shares marine border with Russia?
(A) Florida
(B) Hawaii
(C) Georgia
(D) Alaska

The answer is: (D)