Answer:
a)
And we can find the individual probabilities like this:
And replacing we got:
b)
Step-by-step explanation:
Let X the random variable that represent the number of hurricanes hitting the coast of Florida annualle. We know that
The probability mass function for the random variable is given by:
And f(x)=0 for other case.
For this distribution the expected value is the same parameter
Part a
For this case we want this probability:
And for this case we can use the complement rule like this:
And we can find the individual probabilities like this:
And replacing we got:
Part b
Using the probability mass function we have:
For the same reasons as the last problem...
s(n)=20(1-(1/2)^n)/(1-1/2)
s(n)=40(1-(1/2)^n)
But this time we are not starting at one so we must subtract the sum of s(2) from the sum of s(12) so:
40((1-(1/2)^12-(1-(1/2)^2)
40(0.249755859375)
≈9.99 (to nearest one-thousandth)
You just divide the numbers
So if you have 2/4 you would do 2 divided by 4 and get 0.5