Answer:
--- Standard deviation
Step-by-step explanation:
Given
See attachment for graph
Solving (a): Explain how the standard deviation is calculated.
<u>Start by calculating the mean</u>
To do this, we divide the sum of the products of grade and number of students by the total number of students;
i.e.

So, we have:



Next, calculate the variance using the following formula:

i.e subtract the mean from each dataset; take the squares; add up the squares; then divide the sum by the number of dataset
So, we have:



Lastly, take the square root of the variance to get the standard deviation


--- approximated
<em>Hence, the standard deviation is approximately 11.28</em>
Considering the calculated mean (i.e. 82.76), the standard deviation (i.e. 11.28) is small and this means that the grade of the students are close to the average grade.
Answer:
x=7
Step-by-step explanation:
Simplifying
3x + 2(4 + 6x) = 113
3x + (4 * 2 + 6x * 2) = 113
3x + (8 + 12x) = 113
Reorder the terms:
8 + 3x + 12x = 113
Combine like terms: 3x + 12x = 15x
8 + 15x = 113
Solving
8 + 15x = 113
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-8' to each side of the equation.
8 + -8 + 15x = 113 + -8
Combine like terms: 8 + -8 = 0
0 + 15x = 113 + -8
15x = 113 + -8
Combine like terms: 113 + -8 = 105
15x = 105
Divide each side by '15'.
x = 7
Simplifying
x = 7
Yes due to the fact that additive inverse is the oppsite. so she runs up +4 and runs down -4.
8-4x-7=5x+30-2
combine like terms
1-4x=5x+28
-27=9x
divide both sides by nine
-3=x