# Reading Assignment #12 – Due 3/2/12

1. Water samples are taken from water used for cooling as it is being discharged
from a power plant into a river. It has been determined that as long as the mean temperature of the discharged water is at most 150 degrees Fahrenheit, there will be no negative effects on the river’s ecosystem. To investigate whether the plan is in compliance with the regulations that prohibit a mean discharge water temperature above 150 degrees, 50 water samples will be taken at randomly selected times, and the temperatures of each sample recorded. Identify an appropriate null and alternative hypothesis for this test, and justify your answer.
2. Suppose, in the context of the previous context, the average temperature for the 50 water samples collected was 152 degrees. Why is it too simple just to say that since 152 is greater than 150, the power power plant discharge temperature is higher than it should be?

# Midterm Corrections

As I announced in class on Friday, I’m letting you turn in corrections to earn a few points back on your first midterm exam. To do so, turn in your original midterm along with corrections to any problem on which you lost points. Your corrections should be on separate paper from your original midterm. For the multiple-choice questions, your corrections should include not only the correct answer, but also a correct explanation for that answer.

Corrections are due in class on Friday, March 2nd. You’ll be able to earn up to 1/3 points back via corrections. So, for instance, if you made a 70 on the midterm, you can earn up to (100 – 70)/3 = 10 points back on your midterm grade.

You are not allowed to work together on your corrections. Doing so will be considered a violation of the Vanderbilt Honor Code. If you need help on your corrections, come see me or one of our TAs.

# Reading Assignment #11 – Due 2/27/12

1. Suppose that a random sample of 50 bottles of a particular brand of cough syrup is selected and the alcohol content of each bottle is determined. Let μ denote the average alcohol content for the population of all bottles of the brand under study. Suppose that the resulting 95% confidence interval is (7.5, 9.4). Would a 90% confidence interval calculated from this same sample have been narrower or wider than the given interval? Explain your reasoning.
2. Suppose a random sample of 30 Vanderbilt undergraduates is found to have an average height of 67 inches and a sample standard deviation of 3 inches. Construct a 95% confidence interval for the average height of the population of all Vanderbilt undergraduates and interpret its meaning.

# Social Bookmarking Assignment #4 – Due 2/24/12

For your next social bookmarking assignment, find and bookmark an example of statistics used in an engineering context. If you’re an engineering major, you’re encouraged (but not required) to find an example associated with your particular major.

For Diigo users, tag your bookmark with “engineering.” For Pinterest users, include the hashtag “#engineering” in your bookmark’s description.

To get credit for this assignment, complete it by Friday, February 24th, before class begins.

Image: “Interesting Pin,” Derek Bruff, Flickr (CC)

# Reading Assignment #10 – Due 2/20/12

Here’s your next reading assignment. Read this short article on geostatistics by 8 a.m., Monday, February 20th. Be sure to login (using the link near the bottom of the sidebar) to the blog before leaving your answers in the comment section below.

1. In this course, we’ve focused on the difference between a population and a sample drawn from that population. In the example in the article about rainfall in Sweden, what is the population and what is the sample?
2. Suppose that in 1993 you selected a citizen of Belarus at random and tested the milk in his or her refrigerator for radiocesium. What are some reasons the level of radiocesium might vary from citizen to citizen?  Which of these reasons would be relatively easy to model mathematically?