Question 406179
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Hi
the 98% confidence interval is two-tailed, .01 on the right and left:
	&#945;	&#945;/2	crtical regions	
98%	2%	1%	z <-2.33	z >+2.33   NORMSINV(0.01)= 2.3263
Note graph: between the two blue lines represents 98% of the distribution
{{{drawing(300,300,-5,5,-1,1,blue(line(2.33,5,2.33,-5)), blue(line(-2.33,5,-2.33,-5)),grid(1),graph( 300, 300,-5,5,-1,1,(1/sqrt(2*pi))*3^((-x^2/2)))) }}}

If a population has a standard deviation &#963; of 25 units, what is the standard error of the mean 
if samples of size 16 are selected? Samples of size 36? Samples of size 100?
&#963;[M] = [25/sqrt(16)] 		
&#963;[M] = [25/sqrt(36)]
&#963;[M] = [25/sqrt(100)]