find the critical value za/2 that corresponds to 99% confidence level

Question

99% confidence level

Answer 1

-2.575

Answer 2

Do one of the following, as appropriate . (a) Find the critica value z a/2; (b) find the critica value t a/2; (c) state that neither the normal nor the t distribution applies. Confidence level 99%; n=22; sigma is unknown; population appears to be normally distributed.

a. t a/2 = 2.518

b. t a/2 = 2.831

c. z a/2 = 2.33

d. z a/2 = 2.575

e. Neither normal nor t distribution applies.

I need to know how to get the answers..

Answer 3

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

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