Standard Deviation Problem below. Can anyone figure out the solution?

What is the 98% confidence interval for the standard deviation, sigma , of birth weights at County General Hospital, if the standard deviation of the last 22 babies born there was 1.8 pounds?





a. 1.20 %26lt; sigma %26lt; 2.02





b. 1.15 %26lt; sigma %26lt; 2.14





c. 1.10 %26lt; sigma %26lt;2.30





d. 1.07 %26lt; sigma %26lt; 2.43





e. 1.28 %26lt; sigma %26lt; 2.91





f. 1.32 %26lt; sigma %26lt; 2.77





g. none of these

Standard Deviation Problem below. Can anyone figure out the solution?
%26gt;%26gt; Since none of choices a-f is centered around 1.8,


%26gt;%26gt; I would go with (g).


%26gt;%26gt;


%26gt;%26gt; Dan





I was thinking of the naive measured mean +/- standard error for means when I wrote that. But checking it out, in a million random trials of 22 generated normals with sigma 1.32, the measured "(n-1)/n" sample standard deviation was %26gt;= 1.8 about 0.98% of the time. For sigma 2.77 the meaured standard deviation was %26lt;= 1.8 about 0.97% of the time.





So the answer is (f), 1.32 %26lt; sigma %26lt; 2.77





Dan