Answer:
a
The average cost is

b
The standard deviation of cost is
Explanation:
From the question we are told that




The cost of replacing the two component is C = 50 + 2 X + 4 Y
The variance of X is mathematically represented as
V(X) =
Substituting values
![V[X] = 24 - 4^2](https://img.qammunity.org/2021/formulas/mathematics/college/e5ybqdij6gqu38enxqlkdffhwuhy9zuwhn.png)
![V[X] =8](https://img.qammunity.org/2021/formulas/mathematics/college/8ptlrqtudedopkii9o69mgaj1bu9i0ysu1.png)
The variance of Y is mathematically represented as
V(Y) =
Substituting values
![V[Y] = 8 - 2^2](https://img.qammunity.org/2021/formulas/mathematics/college/afpjzslu6v22rkwrugbet89zd50futrp6h.png)
![V[X] =4](https://img.qammunity.org/2021/formulas/mathematics/college/aehz7mo8enyiidxl8kwfbs1mxqbbi8s6kj.png)
The average of replacing the two component is

substituting value


The variance of replacing the two component is
Note: The variance of constant is zero
and X and Y are independent
=>

substituting values
=>
=>
=>

The standard deviation is
substituting values