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Unformatted text preview: MAT 121 Final Exam December 14, 2005 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. Make sure you have seen and understand the material in the
syllabus about what sort of notes you are allowed to put in your book. 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 classify. (i) President Bush is a Republican (Republican) (ii) 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) i wish to know how SU students feel about statistics so i ask a few
people in this class. 3. (12 points) Men's weights are normally distributed with a mean of 172 pounds
and a standard deviation of 29 pounds. We wish to design an elevator to safely
carry 14 people. Find the maximum total allowable weight if we want a 95%
probability that this maximum will not be exceeded when 14 men are randomly selected.
4. (12 points) Pumpkin weights are normally distributed with a mean of 21 pounds and a standard deviation of 3 pounds. If one pumpkin is chosen at
random, what is the probability that its weight is between 19 and 23 pounds? Go to next page MAT 121 Final Exam December 14, 2005 Version 1 Page 2 5. (12 points) Consider the following table, which describes the imaginary
sinking of the imaginary boat the Miniscule. Men Women Boys Girls
Survived 21 13 2 3
Died 1 1 16 4 5 (a) If one of the Miniscule passengers is randomly selected, find the probability of
getting a boy or someone who survived the sinking. (b) If we randomly select someone who was aboard the Miniscule, what is the
probability of getting a woman, given that the selected person died? 6. (10 points) A simple random sample of 26 medicine pills has a mean weight of
2.4 grams with a sample standard deviation of 0.3 grams. Find a 99% confidence
interval for the standard deviation of the weights of all the pills. Assume pill
weights are normally distributed. 7. (12 points) For the following list of data: (a) Compute the 20m percentile.
(b) Compute the percentile of the data value 15. 5 7 9 1O 11 12 14 15 17 8. (10 points) You wish to make a confidence interval for the proportion of people
with red hair in a certain state. You want the confidence level to be 97% and the
error to be 0.02. No prior estimate of the proportion is available. What should your sample size be? 9. (1 0 points) in a certain state 30% of the voters are Democrats.
(a) Find the mean and standard deviation for the number of Democrats in groups of 1000 voters from that state.
(b) If a group of 1000 voters from that state had 250 Democrats, would that be considered unusual? Why? 10. (10 points) Passwords are made according to the following rules. Each
password has 4 characters. The first two are letters of the alphabet, repeats
allowed. The last two are single digit numbers, 0 - 9, repeats allowed. How many different passwords are possible? ...
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This note was uploaded on 06/19/2011 for the course MATH 121 taught by Professor Na during the Spring '11 term at University of North Carolina School of the Arts.
- Spring '11