Answer:


The confidence interval of standard deviation is:
to 
Step-by-step explanation:
Given

See attachment for the formatted data
Solving (a): The mean
This is calculated as:

So, we have:




Solving (b): The standard deviation
This is calculated as:




--- approximated
Solving (c): 95% confidence interval of standard deviation
We have:

So:



Calculate the degree of freedom (df)



Determine the critical value at row
and columns
and 
So, we have:
---- at 
--- at 
So, the confidence interval of the standard deviation is:
to 
to 
to 
to 
Answer:
n = 8√2
Step-by-step explanation:
It's a 30-60-90 triangle, so n = 2×4√6/√3 = 8√2
Answer:
b. 0.86, 0.87
Step-by-step explanation:
a. Find attached solution to a