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99% , 1%/2 = .5% and invNorm(.005)= 2.58
a a/2 2-tailed crtical regions
80% 0.2 10% z <-1.28155 z >+1.28155
90% 0.1 5% z <-1.645 z >+1.645
92% 0.08 4% z <-1.751 z >+1.751
95% 0.05 2.50% z <-1.96 z >+1.96
98% 0.02 1% z <-2.326 z >+2.326
99% 0.01 0.5% z<-2.576 z >+2.576