Answer:
Step-by-step explanation:
To find the population variance, we first need the mean:
so the mean is 7.2. To find the population variance (which is almost exactly the same as the sample variance except for a small difference in the denominators of the formula) we have to take each number minus the mean, and then square the difference. Add together all these squared numbers and then divide by the number of numbers. Like this:
Add together those numbers and divide them by 5:
![\sigma=\frac{10.24+1.44+.64+3.24+3.24}{5}=\frac{18.8}{5}=3.76](https://tex.z-dn.net/?f=%5Csigma%3D%5Cfrac%7B10.24%2B1.44%2B.64%2B3.24%2B3.24%7D%7B5%7D%3D%5Cfrac%7B18.8%7D%7B5%7D%3D3.76)
First add the prices of the original books.
2.5+4.95+6=11.45
Find 20% of 11.45
=2.29
Therefore I saved $2.29
What we have here in the picture is a graph of a segment. The goal is to find the segment's length, which we can do by using the distance formula:
![d^2=(x_2-x_1)^2-(y_2-y_1)^2](https://tex.z-dn.net/?f=d%5E2%3D%28x_2-x_1%29%5E2-%28y_2-y_1%29%5E2)
Note that the distance between two points is equal to the length of the line segment that joins them.
So now we already have answers for two of the boxes.
The difference in the x-coordinates gives us the horizontal distance between the two points, while the difference in the y-coordinates gives us the vertical distance between the points.
So, the other two boxes should contain:
Z - 7 = 8
subtract 7 from both sides
z = 15
hope this helped!