# Practice Midterm

Pages: 4 (551 words) Published: March 30, 2013
Statistics 503, Fall 2009, Practice Midterm 2
Time: 1 hour

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Show all your work and calculations. Partial credit will be given for work that is partially correct. Points will be deducted for false statements shown in the solution to a problem, even if the final answer is correct. Numbers in the right-hand margin indicate the number of points for each question. If extra space is needed, use the back of a page and indicate this clearly on the question page.

This exam is closed-book. You may not consult any notes or books during this exam. One formula page, and tables are provided separately. Calculators are permitted.

Please sign below to indicate your agreement with the following honour code. Honour code: I promise not to cheat on this exam. I will neither give nor receive any unauthorized assistance. I promise not to share information about this exam with anyone who may be taking it at a different time. I have not been told anything about the exam by someone who has already taken it.

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Date:

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1. In a study of anemia in cattle, researchers measured concentration of selenium in blood of 36 cows that had been given a dietary supplement of selenium. The cows were of the same breed (Santa Gertrudis) and had borne their first calf during the year. The mean selenium concentration was 6.21 µ g/mLi and the standard deviation was 1.84 µg/mLi.

a) Construct a 95% confidence interval for the population mean.

b) Interpret in words your confidence interval found above.

c) Estimate how many cows should be used in the study for the standard error of the sample mean to be smaller than 0.2 µ g/mLi?

caffeine
28

26

11

1

-3

0

14

-4

-2

-4

-4

14

18

16

2

8

2

2. Researchers studied the short-term effect that caffeine has on heart rate. A group of twenty volunteers drank six ounces of coffee. Nine of the subjects were given coffee containing caffeine and eleven...