A company manufacturing CDs is working on a new technology A

A company manufacturing CDs is working on a new technology. A random sample of 703 Internet users were asked:

Given a=1-0.9=0.1, Z(0.05) = 1.645 (from standard normal table)

So the lower bound is

p - Z*sqrt(p*(1-p)/n )= 0.64-1.645*sqrt(0.64*(1-0.64)/703) = 0.6102197

So the upper bound is

p + Z*sqrt(p*(1-p)/n )= 0.64+1.645*sqrt(0.64*(1-0.64)/703) = 0.6697803

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margin of error= (Z*sqrt(p*(1-p)/n )) /2

=1.645*sqrt(0.64*(1-0.64)/703)/2

=0.01489016

So n=(Z/E)^2*p*(1-p)

=(1.645/0.01489016)^2*0.64*(1-0.64)

=2812.002

Take n=2813