Answer:
I believe the answer is 20.
Step-by-step explanation:
Using addition of variables, it is found that the mean of S is of 73 and the standard deviation is of 8.5.
<h3>What happens to the mean and the standard deviation when two variables are added?</h3>
- The mean is the sum of the means.
- The standard deviation is the square root of the sum of variances.
In this problem, for variables A and B, we have that:


Variable S is the sum of A and B, hence:


The mean of S is of 73 and the standard deviation is of 8.5.
More can be learned about addition of variables at brainly.com/question/26156502
Answer:
y=-8
x=-7
Step-by-step explanation:
x-2y=9 x=2y+9
3x-5y=19
3(2y+9)-5y=19
6y+27-5y=19
y+27=19
y=-8
x=2(-8)+9=-16+9=-7
Answer:
8 4 2 0
Step-by-step explanation:
Answer:
27 pages.
Step-by-step explanation:
100% = 45 pages
1% = 45 / 100 = 0.45
pages left = 100% - 40% = 60%
so, 0.45 × 60 = 27.