Its b and a hope this helps
Answer:
2 step equation problems.
Step-by-step explanation:
So you need to replace -3 into that to add -18 on both sides and that gives you the negative number is -20 and then you add the -5r+-3r less than or equal to -20. Now, negative -5 +3 = -8 + -20 = -28. r=-28.
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:

Answer:
0.45576
Step-by-step explanation:
z = (x-μ)/σ, where
x is the raw score
μ is the population mean
σ is the population standard deviation.
Standard Deviation = √variance
Mean = 50
= √9
= 3
z = 51 - 50/3
= 0.11111
Probability value from Z-Table:
P(x<51) = 0.54424
P(x>51) = 1 - P(x<51)
= 1 - 0.54424
= 0.45576
The probability that the dealer will sell 51 or more cars is 0.45576