2 answers
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ME=Zā(0.25/n)
For 90% confidence level, and ME=1%
Z=1.644854 [ from tables for two tale at 95%]
=>
0.01=1.644854ā(0.25/n)
=>
n=(1.644854/0.01)^2*0.5
=6763.86 ~ 6764 persons