Answer:
$7
Step-by-step explanation:
Your two equations are ...
Double the second equation and subtract the first:
2(2s +4t) -(4s +6t) = 2(42) -(70)
2t = 14 . . . . . simplify
t = 7 . . . . . . . divide by 2
The cost of each tie is $7.
Answer:
Step-by-step explanation:

the answer to this would be C I hope this helps :)
Answer:

Now we can find the second central moment with this formula:

And replacing we got:

And the variance is given by:
![Var(X) = E(X^2) - [E(X)]^2](https://tex.z-dn.net/?f=%20Var%28X%29%20%3D%20E%28X%5E2%29%20-%20%5BE%28X%29%5D%5E2)
And replacing we got:

And finally the deviation would be:

Step-by-step explanation:
We can define the random variable of interest X as the return from a stock and we know the following conditions:
represent the result if the economy improves
represent the result if we have a recession
We want to find the standard deviation for the returns on the stock. We need to begin finding the mean with this formula:

And replacing the data given we got:

Now we can find the second central moment with this formula:

And replacing we got:

And the variance is given by:
![Var(X) = E(X^2) - [E(X)]^2](https://tex.z-dn.net/?f=%20Var%28X%29%20%3D%20E%28X%5E2%29%20-%20%5BE%28X%29%5D%5E2)
And replacing we got:

And finally the deviation would be:
