This should be the answer.
 
        
        
        
Answer:
2.275%
Step-by-step explanation:
The first thing to do here is to calculate the z-score
Mathematically;
z-score = (x-mean)/SD
from the question, x = 12,300 hours , mean = 11,500 hours while Standard deviation(SD) = 400 hours
Plugging the values we have;
z-score = (12,300-11,500)/400 = 800/400 = 2
Now, we want to calculate P(z ≤ 2)
This is so because we are calculating within a particular value 
To calculate this, we use the z-score table.
Mathematically;
 P(z ≤ 2) = 1 - P(z > 2) = 1 - 0.97725 = 0.02275
To percentage = 2.275%
 
        
             
        
        
        
Answer:
1/2
Step-by-step explanation:
 
        
             
        
        
        
Answer:
d. (10,800)
Step-by-step explanation:
Vertex appears to be at x = 10
Vertex: (10,800)
 
        
             
        
        
        
Answer:
AB = 8/ cos 60
Step-by-step explanation:
We want to find the hypotenuse AB
Since we have a right triangle
cos theta = adj/ hyp
cos 60 =  8/ AB
AB cos 60 = 8
AB = 8/ cos 60