Wetzel

Math 120

Chapter 6

Confidence Intervals –

            A.)  Large Sample 

                        1.)  Find .

                        2.)  Find the z-score corresponding with the given confidence level.

                        3.)  Find the error. 

                        4.)  Construct the interval

            B.)  Small Sample 

                        1.)  Find .

                        2.)  Determine the Degrees of Freedom.

                                                d.f. = n – 1

                        3.)  Find the t – score.

                        4.)  Find the error.  

                        5.)  Construct the interval

            C.)  Proportion  (percent)

                        1.)  Find

                        2.)  Find the z-score corresponding with the given confidence level.

                        3.)  Find the error. 

                        4.)  Construct the interval

Determining the Minimum Sample Size –

                        A.)  Mean & Standard Deviation:

                        B.)  Proportion: