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:



Part A:
3.14 X (4)^2 X 3/3
= 50.26548246
I think the answer is B. 150 i may be wrong though
Answer:
25m
Step-by-step explanation:
Shannon's rate is 2,500m/100min. Simplifying, we see that this is equal to 25m/1min.
So, she walks 25 m in one minute.