Question

Supposed you were asked to estimate the proportion of 25-30 year olds that have a home (land line) telephone. In order to make this estimate, you polled 600 people in this age range and the bellows were reported below: [25] pts. Total]

            Home Phone              Frequency

            NO                                    450

            YES                                  150

                                                        600

1. What is the proportion of the sample that report YES, they have a home phone line? [5 pts]

2. What condition must be met in order to calculate a confidence interval to estimate this proportion? Is this condition met? [5 pts.]

3. Develop a 95% confidence interval for the proportion of all of 25-30 year olds that have a home (land line) telephone

Answer 1

1) the proportion of the sample that reports YES, they have a home phone line =

2) The following condition must be met in order to calculate a confidence interval to estimate this proportion.

1. The sampling method is simple random sampling.
2. The sample is sufficiently large. As a rule of thumb, a sample is considered "sufficiently large" if it includes at least 10 successes and 10 failures.

3)