Answer:
$5.24
Step-by-step explanation:
If Mom bought 4, she bought
worth of pie filling. Since she paid $10, she needs
change
I don’t think it would work it you solved for k instead of y. Because you’re solving for y when you do constant of proportionality. i’m not sure if i’m right or not but that’s what i think.
Answer:you just need to divided 135÷ 6
Step-by-step explanation:
Answer:
B. 1 out of 5,005
Step-by-step explanation:
Given
Number of Friends = 15
Required
Probability of selecting 6 friends
The first step is to calculate the number of ways 6 friends can be selected
The keyword in the above statement is selection;
This implies combination;
The number of ways is calculated as follows;
![\left[\begin{array}{c}n&r&\end{array}\right] = \frac{n!}{(n-r)!r!}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7Dn%26r%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7Bn%21%7D%7B%28n-r%29%21r%21%7D)
Where n = 15 and r = 6
![\left[\begin{array}{c}n&r&\end{array}\right] = \frac{n!}{(n-r)!r!}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7Dn%26r%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7Bn%21%7D%7B%28n-r%29%21r%21%7D)
becomes
![\left[\begin{array}{c}15&6&\end{array}\right] = \frac{15!}{(15-6)!6!}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7B15%21%7D%7B%2815-6%29%216%21%7D)
![\left[\begin{array}{c}15&6&\end{array}\right] = \frac{15!}{9!6!}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7B15%21%7D%7B9%216%21%7D)
![\left[\begin{array}{c}15&6&\end{array}\right] = \frac{15 * 14 * 13 * 12 * 11 *10 * 9!}{9! *6 * 5 * 4 * 3 * 2 * 1}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7B15%20%2A%2014%20%2A%2013%20%2A%2012%20%2A%2011%20%2A10%20%2A%209%21%7D%7B9%21%20%2A6%20%2A%205%20%2A%204%20%2A%203%20%2A%202%20%2A%201%7D)
![\left[\begin{array}{c}15&6&\end{array}\right] = \frac{15 * 14 * 13 * 12 * 11 *10}{6 * 5 * 4 * 3 * 2 * 1}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7B15%20%2A%2014%20%2A%2013%20%2A%2012%20%2A%2011%20%2A10%7D%7B6%20%2A%205%20%2A%204%20%2A%203%20%2A%202%20%2A%201%7D)
![\left[\begin{array}{c}15&6&\end{array}\right] = \frac{3603600}{720}](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D%20%5Cfrac%7B3603600%7D%7B720%7D)
![\left[\begin{array}{c}15&6&\end{array}\right] =5005](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bc%7D15%266%26%5Cend%7Barray%7D%5Cright%5D%20%3D5005)
Hence, there are 5005 ways of selecting 6 from 15 friends
Since, there's only one way of selecting the 6 named friends
Then, the probability is 1 out of 5,005
Answer:
Step-by-step explanation:
We have by definition
![Cov(X,Y) = E[(x – M_x)(Y – M_y)]](https://tex.z-dn.net/?f=Cov%28X%2CY%29%20%3D%20E%5B%28x%20%E2%80%93%20M_x%29%28Y%20%E2%80%93%20M_y%29%5D)
where Mx and My are means of X and Y respectively
a) ![E[(x – M_x)(Y – M_y)]\\= E(x,y) - E(x,My)-E(y,Mx)+M_x M_y\\=E(x,y) -E(x) M_y -E(y) M_x +M_x M_y\\=E(x,y)-M_x M_y-M_x M_y+M_x M_y\\=E(x,y)-M_x M_y](https://tex.z-dn.net/?f=E%5B%28x%20%E2%80%93%20M_x%29%28Y%20%E2%80%93%20M_y%29%5D%5C%5C%3D%20E%28x%2Cy%29%20-%20E%28x%2CMy%29-E%28y%2CMx%29%2BM_x%20M_y%5C%5C%3DE%28x%2Cy%29%20-E%28x%29%20M_y%20-E%28y%29%20M_x%20%2BM_x%20M_y%5C%5C%3DE%28x%2Cy%29-M_x%20M_y-M_x%20M_y%2BM_x%20M_y%5C%5C%3DE%28x%2Cy%29-M_x%20M_y)
b) Since right side inside expectation is commutative, we get cov(x,y) = cov (y,x)
c) 
d) 
f) Var(x+y) = 
Expanding inside we get
=