Random Variable and Mathematical Expectation One Mark Question

12th Standard EM

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Time : 00:30:00 Hrs
Total Marks : 10
10 x 1 = 10
1. Value which is obtained by multiplying possible values of random variable with probability of occurrence and is equal to weighted average is called

(a)

Discrete value

(b)

Weighted value

(c)

Expected value

(d)

Cumulative value

2. Demand of products per day for three days are 21, 19, 22 units and their respective probabilities are 0⋅ 29, 0⋅ 40, 0⋅ 35. Pofit per unit is 0⋅ 50 paisa then expected profits for three days are

(a)

21, 19, 22

(b)

21.5, 19.5, 22.5

(c)

0.29, 0.40, 0.35

(d)

3.045, 3.8, 3.85

3. Probability which explains x is equal to or less than particular value is classified as

(a)

discrete probability

(b)

cumulative probability

(c)

marginal probability

(d)

continuous probability

4. Given E(X) = 5 and E(Y) = -2, then E(X – Y) is

(a)

3

(b)

5

(c)

7

5. A variable that can assume any possible value between two points is called

(a)

discrete random variable

(b)

continuous random variable

(c)

discrete sample space

(d)

random variable

6. A formula or equation used to represent the probability distribution of a continuous random variable is called

(a)

probability distribution

(b)

distribution function

(c)

probability density function

(d)

mathematical expectation

7. If X is a discrete random variable and p x ( ) is the probability of X , then the expected value of this random variable is equal to

(a)

$\sum { f(x) }$

(b)

$\sum { [x+f(x)] }$

(c)

$\sum { f(x)+x }$

(d)

$\sum { xp(x) }$

8. Which of the following is not possible in probability distribution?

(a)

$\sum { p(x)\ge 0 }$

(b)

$\sum { p(x)=1 }$

(c)

$\sum { xp(x)=2 }$

(d)

$p(x)=-0.5$

9. If c is a constant, then E(c) is

(a)

0

(b)

1

(c)

cfc

(d)

c

10. A discrete probability distribution may be represented by

(a)

table

(b)

graph

(c)

mathematical equation

(d)

all of these