Answer:

Step-by-step explanation:
Independent events:
If two events, A and B are independent, the probability of both A and B happening is the same as the probability of A happening multiplied by the probability of B happenings, that is:

In this question:
The statement is 
Hey, I think an image is needed to answer this question.
Answer:

Step-by-step explanation:
Since the sequence is geometric (it multiplies the previous number each time). The nth term sequence would be 
Because the sequence multiplies by 3 each time, The base number in that equation would be
.
So
of the equation would be:
.
Compare the 2 equations:
4, 12, 36
3, 9 ,27
The difference between the 2 equations is: 1, 3, 9 which itself is a geometric sequence so the nth term of this new equation is:
.
Combine these 2 equations together and you get:
.
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:
search up-area of circle formula and circumference of a circle formula
Step-by-step explanation: