Do one of the? following, as appropriate.? (a) Find the critical value z Subscript alpha divided by 2 zα/2?, ?(b) find the critical value t Subscript alpha divided by 2 tα/2?, ?(c) state that neither the normal nor the t distribution applies. Confidence level 90 nequals =27 sigma is unknown σ is unknown?; population appears to be normally distributed.