Question 1197540
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Hi  
 98% confident  ⇒  z = 2.326 (See below)
σ = $21.8,   ME = 2
How large of a sample size is required? 
ME large relative to  σ  ... Expect Sample size to be small
{{{ME = z*sigma/sqrt(n)}}}
0r
n = {{{( z*sigma/ME)^2}}}
n = {{{((2.326*21.80)/(2)^2 ))}}} = 12.7  0r sample Size = 13 (always round Up)

 = CI	z = value
90%	z =1.645  
92%	z = 1.751
95%	z = 1.96   
98%	z = 2.326   Invnorm(.99)  2-sided (.98 + .02/2 = .99 ) 
99%	z = 2.576
Wish You the Best in your Studies.
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