Compute the critical value zalpha2 that corresponds to a 87

Compute the critical value z_alpha/2 that corresponds to a 87% level of confidence.

Solution

As c = 0.87, then

alpha/2 = (1-c)/2 = (1-0.87)/2 = 0.065

Hence, using the InvNorm function of a ti84,

InvNorm(0.065,0,1)

to get

z(alpha/2) = 1.514101888 = 1.51 [ANSWER, ignoring the - sign]