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Unformatted text preview: MAT 121 Final Exam December 16, 2004 Version 1 Page 1 There are 10 questions. Do all parts of all questions. Show the work you do to
obtain an answer. A calculator and your textbook are allowed. No other books or
notes are allowed. Do not share calculators. Name: Put your name on your blue book. Put all the work you wish to have graded in
your blue book. Turn in both your exam and your blue book together. When you turn in your exam make sure your name gets checked off the list as
having turned in the exam. 1. (6 points) In each case tell whether the information given is at the nominal,
ordinal, interval, or ratio level of measurement. The number or word in
parentheses indicates what data you are to classsify. (a) President Bush is a Republican. (Republican) (b) The term of office for a President is 4 years. (4) 2. (6 points) in each case tell whether the sample is being selected by random, systematic, cluster, stratified, or convenience sampling.
(a) A marketing firm wishes to conduct a mail survey of the country. It randomly selects 50 different zip codes, then mails the survey to everyone in each zip code.
(b) | wish to know how SU students feel about statistics so I ask a few people in this class. 3. (12 points) In a certain swamp 5% of the mosquitoes carry the West Nile virus. Suppose 9 of the mosquitoes are chosen at random.
(a) What is the probability that exactly two of them carry the West Nile virus?
(b) What is the probability that less than two of them carry the West Nile virus? 4. (10 points) The heights of corn stalks in a certain field are normally distributed
with a mean of 7.3 feet and a standard deviation of 2.1 feet. Find the 90th
percentile, that is, the height that separates the shortest 90% from the tallest 10%. 5. (12 points) In a simple random pre-eleotion poll of 1400 voters 800 say they
intend to vote for candidate A. Construct a 99% confidence interval for the
percentage of all voters who intend to vote for candidate A. Go to next page MAT 121 Final Exam December 16, 2004 Version 1 Page 2 6. (10 points) A researcher wants to estimate the average weight of eggs
produced on a certain farm. The researcher wants to make a confidence interval
for the mean weight, wants the confidence level to be 95% and wants the error to
be at most 20 milligrams. Preliminary studies suggest the standard deviation of
the weights is approximately 420 milligrams. What sample size should the researcher use?
7. (12 points) Consider the following frequency distribution. Weight of Pumpkins (lbs) Number of Pumpkins 0-4 3
15-19 1 C) (a) Find the mean of the weights of the pumpkins.
(b) Find the standard deviation of the weights of the pumpkins. 8. (1 0 points) These are the grades on a test in a class with 16 students. Find the
mean, median, mode and midrange. 52 52 52 56 56 62 65 65
67 76 78 87 87 88 89 98 9. (12 points) The board of directors of a company has 8 members.
(a) How many different possibilities are there for a subcommittee consisting of 3 members?
(b) How many different possibilities are there for choosing a president, vice president, secretary, and treasurer assuming no person can hold more than one
office? 10. (10 points) The weights of a batch of water melons are normally distributed
with a mean of 27.2 lbs and a standard deviation of 4.2 lbs. A simple random
sample of 60 of them is chosen. What is the probability that the mean of the sample is greater than 28 lbs? ...
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