A variable x of a finite population has the following frequency distribution :

x123
f686

Suppose a member is selected at random from the population and let X denote the value of the variable x for the member obtained.

a. Determine the probability distribution of the random variable X.

b. Use random-variable notation to describe the events that X takes on the value 2, a value of at most 2, and a value greater than 2.

c. Find P(X = 2), P(X 2), and P(X > 2). Interpret your results.

d. Construct a probability histogram for the random variable X.

Short Answer

Expert verified

Part a.

Random Variable (X)Probability
16/20 = 0.3
28/20 = 0.4
36/20 = 0.3

Part b.

On the value of 2: X = 2

A value of at most 2 : X 2

A value greater than 2: X > 2

Part c.

P(X=2)=0.4P(X2)=0.3+0.4=0.7P(X>2)=0.3

Part d.

Step by step solution

01

Part (a) Step 1. Given information

The frequency distribution of a variable x in a finite population is as follows:

x123
f689

Let X signify the value of the variable x for the member acquired if a member is chosen at random from the population.

02

Part (a) Step 2. Formula Used

The experiment is conducted out assuming that the random variable (X=x) occurs n times out of a total of N times. As a result of the fNrule:

P(X=x)=nN

03

Part (a) Step 3. Solution

Here ,N=6+8+6=20. As a result, the probability of random variable X is as follows:

Random Variable

Probability

1

620=0.3

2

820=0.4

3

620=0.3

04

Part (b) Step 1. Solution 

Event that X takes the value 2, can also be written as :

X = 2

Event that X takes a value of at most 2, can also be written as :

X 2

Event that X takes a value greater than 2, can also be written as:

X > 2

05

Part (c) Step 1. Solution

From the table, we get :

P(X=2)=0.4P(X2)=0.3+0.4=0.7P(X>2)=0.3

06

Part (d) Step 1. Solution

The probability histogram for the random variable X is as follows:

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