statistic assignment 4

 

Answer all questions. Show all calculations. Explain clearly and completely.

1.  A statewide poll for an upcoming gubernatorial election concluded that 52.8% of the voters will vote for candidate A and 47.1% will vote for candidate B. The margin of error is ±2.5%. The confidence level for this result is 95%.

1a. Explain the Confidence Interval.  (3 pts.)

1b. Explain the difference between the Confidence Interval and the Confidence Level.  (5 pts.) 

1c.  Explain what happens to the Confidence Level when the Confidence Interval is increased (widened).  (4 pts.)

1d.  Is the poll result predicting a win for either candidate (A or B)? Explain.  (5 pts.)

1e.  Explain at least two reasons that could cause these poll results to be inaccurate,biased or unreliable.  (8 pts.)

2.  A university president claims that on average, at least 60% of incoming freshman students go on to earn their degrees and graduate from the university.

For the hypothesis test, a random sample of 50 freshman students were selected for a sample study. 27 of them graduated with their degrees. 27 out of 50 is 54%. 

The test statistic (formula result) is z = -1.46.

The p-value for this test statistic is .0721 or 7.21%.

2a. Explain is the parameter of interest?  (3 pts)

2b.  Explain the Null Hypothesis.  (4 pts.)

2c.  Explain the Alternative Hypothesis.  (4 pts.)

2d.  Based on the test statistic, z, and the p-value, explain whether we should accept or reject the Null hypothesis.  (6 pts.)

2e.  Explain in your own words what the conclusion in 2d says about the result of the test and the action to be taken. (8 pts)