|
Homework assignment |
Please complete the
following homework assignment from the textbook and deliver to me (via e-mail,
us mail, fax or by hand) by March 9, 2000. Note section 5.6 is not included in
this set (it is fun, but not necessary for our purposes)
|
HW #5: |
p. 240: 1,3,5,7,9,11,13,15,17,19,21,23,25 27,29,31, 33,35, 38 p. 246: 1,3,6,7,10,12,18,20,22 p. 252: 1,3,5,8,9,12,14 p. 262: 1-4,6,11,15,17,19,20 p. 301: 1-5,9-11,13,15,17,22,24,27,28 p. 313: 1-5,9,13-16,18,20 p. 321: 1,5,10-16,19,21,24,25 p. 333: 1,5,9-12,16-20 |
Writing Assignment #5
You have seen that a
confidence interval is a range of values that is likely to contain the true
value of a population parameter. Sometimes a claim is made about a population
parameter and if you calculate a confidence interval from a sample you can
conclude how likely the claim is to be true. In each of the problems below,
test the claim concerning the confidence interval by choosing a sample and
calculating the confidence interval. Write up a small paragraph explaining the
validity of the claim using the confidence interval
Problem 1: Sunny Phoenix AZ
Everyone knows that Phoenix
is a warm and sunny spot right?? Go to the web site:
http://ag.arizona.edu/azmet/data/1299em.txt
And test the claim that the
average high temperature in January is 75 degrees. Calculate a confidence
interval for the mean temperature using a 95% degree of confidence. Use a
random sample of 20 average temperatures from the month (you choose them and
describe how you chose them) to calculate the confidence interval
Problem 2: Refinery Smoke
Data
If you live close to a
refinery you might be interested in the amount of Carbon Monoxide produced by
the plant. A refinery in California claims that the mean CO in parts per
million is 75. Use the data at the site below (you only need the first column)
to calculate a confidence interval using a 99% degree of confidence. Use all 40
data points but remember this is still a sample (read the story behind the problem
for why). Investigate the refinery's claim using this confidence interval
http://lib.stat.cmu.edu/DASL/Datafiles/Refinery.html
Problem 3: Montana Politics
Suppose a candidate for office
in Montana claims that only 30% of Montana residents think that the economic
outlook for the state is better than it was a year ago. The site
http://lib.stat.cmu.edu/DASL/Datafiles/montanadat.html
contains data from a survey
of Montana residents (you only need the last column - marked stat). Find a
confidence interval for the proportion of Montana residents who feel the
economic outlook is better than one year ago at the 95% level of confidence.
Comment on the claim made by the candidate. (Note you should assume the data is
recent even though it is not :) )