Answer:
d. 20
Step-by-step explanation:
Standard deviation is 4.5
Margin error for the problem is 2 hours
Probability 95%, that means that the siginficance level α is 1 – p
α = 1 – 0.95 = 0.05
margin of error (ME) can be defined as follows
ME = Z(α/2) * standard deviation/ √n
Where n is the sample size
Z(0.05/2) = Z(0.025)
Using a z table Z = 1.96
Now, replacing in the equation and find n
2 = 1.96 * 4.5/ √n
2 = 8.82/√n
√n = 8.82/2
√n = 4.41
n = 4.41^2
n = 19.44 ≈ 20
 
        
             
        
        
        
Answer:
add a zero at the end of the number. 5x10=50. 60x10=600. 700x10=7000 etc.
Step-by-step explanation:
 
        
                    
             
        
        
        
Bro that's a lot, i don't know what the heck you are talking about.
        
             
        
        
        
Answer:
x = 7
Step-by-step explanation:
-6+7x = -2x+57
+6+2x +2x+6
 9×/9 = 63/9
 × = 7