18/8
8/8
1/8 = 0.125
1+0.125=1.125
Answer:
a) 
With:


b) 

c) 

d) 


Step-by-step explanation:
For this case we know the following propoertis for the random variable X

We select a sample size of n = 81
Part a
Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

With:


Part b
We want this probability:

We can use the z score formula given by:

And if we find the z score for 89 we got:


Part c

We can use the z score formula given by:

And if we find the z score for 75.65 we got:


Part d
We want this probability:

We find the z scores:



Answer:
Yes they are congruent by SAS (wrong answer)
Edit: the correct answer is by HL
Answer:
3^(n+1) - 3^n / 3^(n-1) = 6