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 Practice Past Question And Answers-updatedNow calculate the variance,Benue State Civil Service Practice Past Question And Answers-updated


ENGLISH

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)


GENERAL

1.?The oldest news agency in the world is
(A) AFP
(B) WAFA
(C) BBC
(D) CNN

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)