The Empirical Rule affirm:
99.7 % random variable values are between 
±
three standard deviation.
95 % random variable values are between 
±
 two standard deviation.
68 % random variable values are between 
±
 one standard deviation. There you go!
        
                    
             
        
        
        
<h3>
Answer: Choice A.  x^2+9</h3>
This is a sum of squares, which cannot be factored over the real numbers. You'll need to involve complex numbers to be able to factor, though its likely your teacher hasn't covered that topic yet (though I could be mistaken and your teacher has mentioned it).
Choice B can be factored through the difference of squares rule. Therefore, choice B is not prime. 
Choice C and D can be factored by pulling out the GCF and then use the difference of squares rule afterward. So we can rule out C and D as well.
 
        
        
        
Answer:
N is M reflected across the x-axis; only the signs of the x-coordinates of M and N are different.
Step-by-step explanation:
The y-axis is vertical, and the x-axis is horizontal. If a point, or image, is reflected over the x-axis, in this case M and N, then the signs of the y-coordinates do not change, and instead the coordinates of the x-axis change.
 
        
             
        
        
        
Answer:
Below.
Step-by-step explanation:
log  10  (
100
)  =  2
 
        
                    
             
        
        
        
Answer:
x = 3
Step-by-step explanation:
First, you will pick the first equation :
(x*20)
Then the next,
(x*20) + 5
Then the last equation,
(x*20) + 5 = 5*13
Then you solve
20x + 5 = 65
20x = 65 - 5
20x = 60
20x/20 = 60/20
x = 3