Answer :
Answer:
A. (Table Attached)
B. (See Step 3)
C. 0.06 (See Step 4)
D. NOT independent (See Step 5)
Step-by-step explanation:
STEP 1:
Name the probabilities:
p₁ = 0.02, p₂ = 0.07, p₃ = 0.91
q₁ = 1-p₁ = 0.98 , q₂ = 1-p₂ = 0.93 , q₃ = 0.09
Let X and Y be the number of bits with high and moderate distortion out of three.
STEP 2:
A.
The function will follow multinomial distribution:
[tex]f_{XY}(x,y) = P(X=x, Y=y) = \frac{3!}{x!y!(3-x-y)!} (p_1^x)(p_2^y)(p_3^{3-x-y})[/tex]
Substitute the values and make a table.
TABLE IN ATTACHMENT
STEP 3:
B.
We calculate marginal distribution by:
[tex]P (X=x)=[/tex] ∑ [tex]P(X=x,Y=y)[/tex]
[tex]fx(x)[/tex] can be found by adding all the probabilities in each row for different value of X
For X=0 , ∑P = 0.94157441
For X=1 , ∑P = 0.057624
For X=2 , ∑P = 0.001176
For X=3 , ∑P =0.000008
STEP 4:
C.
The mathematic expectation E is the sum of product of each possibility with its probabiity.
[tex]E(X)=[/tex]∑ [tex]xP(X=x)[/tex]
Find E(X):
[tex]E(X)= (0*0.9415744)+(1*0.057624)+(2*0.001176)+(3*0.000008)[/tex]
[tex]E(X)=0.06[/tex]
STEP 5:
Condition probability states:
[tex]P(A|B)=\frac{P(A,B)}{P(B)}[/tex]
It can also be written as:
[tex]f_{Y|X=1}(y)=\frac{f_{XY}(1,y)}{f_x(1)}[/tex]
Where [tex]f_x(1)\\[/tex] = 0.057624
Calculate the quotient:
[tex]Y|_{x=1}[/tex] = 0 , [tex]f_{Y|_X=1[/tex] = 0.862245
[tex]Y|_{x=1}[/tex] = 1 , [tex]f_{Y|_X=1[/tex] = 0.132653
[tex]Y|_{x=1}[/tex] = 2 , [tex]f_{Y|_X=1[/tex] = 0.000510
[tex]Y|_{x=1}[/tex] = 3 , [tex]f_{Y|_X=1[/tex] = 0
Find the dependency:
[tex]f_{XY}(y)=f_X(x)f_Y(y)[/tex]
We found that
[tex]f_{Y|_X=1[/tex] = 0.862245
Calculate [tex]f_Y(1)[/tex] from summing the column from the table
[tex]f_Y(1)=0.17428341+0.007644+0.000084\\f_Y(1)=0.18201141[/tex]
Which are not equal.
Conclusion:
X and Y are NOT Independent
