Retries
The following table contains the probability distribution for X = the number of retries necessary to successfully transmit a 1024K data package through a double satellite media.
$\begin{array} { | c | c c c c | } \hline \boldsymbol { x } & 0 & 1 & 2 & 3 \\\hline \boldsymbol { p } ( \boldsymbol { x } ) & 0.35 & 0.35 & 0.25 & 0.05 \\\hline\end{array}$
-If X and Y are two variables with $\sigma$ _x = 3.8, $\sigma$ _y = 4.2,and COV(X,Y)= -0.25,then V(X + Y)= 31.58.

Question

Retries
The following table contains the probability distribution for X = the number of retries necessary to successfully transmit a 1024K data package through a double satellite media.

\begin{array} { | c | c c c c | } \hline \boldsymbol { x } & 0 & 1 & 2 & 3 \\\hline \boldsymbol { p } ( \boldsymbol { x } ) & 0.35 & 0.35 & 0.25 & 0.05 \\\hline\end{array}

-If X and Y are two variables with

\sigma

_x = 3.8,

\sigma

_y = 4.2,and COV(X,Y)= -0.25,then V(X + Y)= 31.58.

Quizplus · Accepted Answer

Using the formula for the variance of the sum of two variables, V(X + Y) = V(X) + V(Y) + 2COV(X,Y), and plugging in the given values, we get V(X + Y) = (3.8) + (4.2) + 2(-0.25) = 7.6 - 0.5 = 7.1. Therefore, the statement is false, as the given value of V(X + Y) is not equal to the calculated value.

Retries the Following Table Contains the Probability Distribution for X

Retries
the Following Table Contains the Probability Distribution for X