Do one of the following as appropriate a Find the critical v

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. Confidence level 99 %, n = 17: sigma is unknown; population appears to be normally distributed. Find the critical value.

Solution

As n = 17 is very small (<30), and also sigma is not known. then all the more that we use just t and not z.

Thus, using the table, as

alpha/2 = (1 - c-level)/2 = 0.005,

df = n - 1 = 17 - 1 = 16,

t(alpha/2) = 2.920781622 = 2.921 [ANSWER, OPTION A]