Question 1173268
this is a ChiSq with df=15
(n-1)s^2/CSq lower < sigma^2 < (n-1)s^2/ChiSq upper
from the table, using .05 for the first and 0.95 for the second
15*4.41/24.996 < sigma^2 < 15*4.41/7.261; the 4.41 is 2.1^2
2.65 < sigma ^2 < 9.11 which is the 90% CI for the variance
take the square root of everything to get the 90% CI of the sd
(1.63, 3.02) units months.
The last part of the question is opinion and has a good deal to do with the mean life, which isn't stated.