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
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