Answer: 
Step-by-step explanation:
Given : sample size : n= 51
sample standard deviation : s= 0.46
Significance level : 
Using chi-square distribution, the critical values will be :


Confidence interval for population standard deviation (
) :

Substitute all the values , we get

Hence, the 95% two-sided confidence interval for σ : 
Answer:
Step-by-step explanation:
Age: Frequency:
50-54 2
55-59 5
60-64 3
65-69 3
1.4=h/5
multiply both sides by 5
h=7
Answer. B, (-6,-12)
C, (-11,-12)
A, (-6,-8)