Question 1197458
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Hi  
 90% confident  ⇒  z = 1.645
σ = 30.4,   ME = 5
How large of a sample size is required?
{{{ME = z*sigma/sqrt(n)}}}
0r
n = {{{( z*sigma/ME)^2}}}
n = {{{((1.645*30.4)/5)^2 ))}}} = 100.0320  0r sample Size =101 (always round Up)

 = CI	z = value
90%	z =1.645    Invnorm(.95)  2-sided (.90 + .10/2 = .95 )
92%	z = 1.751
95%	z = 1.96
98%	z = 2.326  
99%	z = 2.576
Wish You the Best in your Studies.
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