Category: Statistics MCQs FPSC NTS PPSC Past Papers Test Questions

(A) expected value
(B) critical value
(C) variance
(D) standard deviation

The answer is: (A) expected value
Explanation
Expectation (or expected value) is the arithmetic mean of all possible outcomes of a random variable.

(A) –1
(B) –0.75
(C) 0
(D) 1.2

The answer is: (D) 1.2
The value of a correlation coefficient is always between –1 and 1, including –1 and 1.

(A) E[X²]
(B) E[X²] – E[X]
(C) E[X²] + E[X]²
(D) E[X²] – E[X]²

The answer is: (D) E[X²] – E[X]²
Explanation
By definition, Var (X) = E[X²] – E[X]²

(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)

The answer is: (C) Var(X) + Var(Y) + 2 Cov(X, Y)
Explanation
By definition, Var (X + Y) = Var(X) + Var(Y) + 2 Cov(X, Y)

(A) 15.5
(B) 17.5
(C) 5.5
(D) 7.5

The answer is: (B) 17.5
Solution
First calculate the mean

Now calculate the variance,

(A) 64.5%
(B) 68.5%
(C) 72.5%
(D) 76.5%

The answer is: (C) 72.5%
Solution
By using formula for calculating weighted average, we have

(A) Normal
(B) Uniform
(C) Poisson
(D) Binomial

The answer is: (A) Normal

(A) 8%
(B) 9%
(C) 10%
(D) 11%

The answer is: (B) 9%
Solution

Data Set-I: 4, 3, 5, 7, 6
Data Set-II: 2, 10, 1, 9, 3
(A) mean and variance are equal
(B) mean and variance are not equal
(C) mean is equal but variance is not
(D) variance is equal but mean is not

The answer is: (C) mean is equal but variance is not
Here, Mean(Data1)=5, Mean(Data2)=5. But, Var(Data1)=2.5, Var(Data2)=17.5

(A) expected value
(B) variance – mean
(C) normal distribution
(D) uniform distribution

The answer is: (A) expected value
If an experiment is repeated independently for a large number of times, it converges to a fixed number/ expected value/ expected distribution.