Answer:
0.36427
Step-by-step explanation:
Mean = λ = 18 messages per hour
P(X = x) = (e^-λ)(λ⁻ˣ)/x!
P(X ≤ x) = Σ (e^-λ)(λ⁻ˣ)/x! (Summation From 0 to x)
But the probability required is that the messages thay come in an hour is between 15 and 20, that is, P(15 < X < 20)
P(15 < X < 20) = P(X < 20) - P(X ≤ 15)
These probabilities will be evaluated using a cumulative frequency calculator.
P(X < 20) = 0.65092
P(X ≤ 15) = poissoncdf(18, 15) = 0.28665
P(15 < X < 20) = P(X < 20) - P(X ≤ 15) = 0.65092 - 0.28665 = 0.36427.
You can use the Poisson distribution calculator here
https://stattrek.com/online-calculator/poisson.aspx
 
        
             
        
        
        
Answer:
C) 16
Step-by-step explanation:

 
        
                    
             
        
        
        
Answer:
look down
Step-by-step explanation:
OK so u take something like 9/3 and then ask how many times the 3 goes into the 9 and that is your whole number. whatever is left is your top of the fraction and the bottom stays the same hope this helped
 
        
                    
             
        
        
        
7.50 dollars because per each mile its $2.50 . and $2.50 times 3 equals $7.50