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 
-2, -4/9 , 34%, 3/8. This is your answer
Answer:
A
Step-by-step explanation:
tan theta will equal zero if theta = n × pi where n is an integer
Answer:
0.25
Step-by-step explanation:
3/12 = 1/4
1÷4= 0.25