A sample size n=200 has a known population standard deviation of 15.0. The population appears to be skewed. Determine whether a margin of error should be calculated using a critical value of za/2, a critical value of ta/2, or neither.

step-by-step explanation:

step-by-step explanation:

we have

using a graphing tool

see the attached figure

this is a quadratic equation (vertical parabola) open up

the vertex is a > vertex

the domain of the function is all real > interval (-∞,∞)

the range of the function is the > [-6.125,∞)

the function has two x->   and

the function is increasing over the > (0.25,∞)

the function is decreasing over the > (-∞,0.25)