Do One of the Following, as Appropriate:
(A) Find $z _ { \alpha / 2 }$

Multiple Choice

Do one of the following, as appropriate:
(a) Find the critical value $z _ { \alpha / 2 }$
(b) find the critical value $t _ { \alpha / 2 }$
(c) state that neither the normal nor the t distribution applies.
90% confidence interval for $\mu$ n=9 ; $\sigma = 4.2$ population appears to be very skewed.

A) $z _ { \alpha / 2 } = 2.896$
B) $z _ { \alpha / 2 } = 2.365$
C) $z _ { \alpha / 2 } = 2.306$
D) Neither the normal nor the t distribution applies.