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Unformatted text preview: MAT 122
FINAL EXAMINATION
DECEMBER 14, 2005 There are 6 questions. Do all parts of all questions. Show the work you do to
obtain an answer. A calculator and your textbook are allowed. Do not share
calculators. Write down all formulas you use. Name: Lab lnstuctor: When you turn in your exam make sure your name gets checked offthe list as
having turned in the exam. 1. (25 points) A poll claims that at least 53% of voters will support John at the
next elections. To test this claim a simple random sample of 1200 voters is obtained and 650 of them said that they would vote for John. At the 0.05 level of
significance, test poll's claim. 2. (25 points) A state inspection of 150 cars in New York found that the brakes in
21 of them needed repairs. A state inspection of 120 cars in Ohio found that the
brakes in 6 of them needed repairs. Use a 0.01 signiﬁcance level to test the claim
that New York has a bigger proportion of cars with defective brakes? 3. (25 points) The table below lists SAT scores of six students before and after a
preparatory course was taken. At the 0.05 level of significance test the claim that,
on average, the preparatory course improves SAT scores. You may assume the
differences are normally distributed. Students A B B B E F
Before 690 840 950 740 1020 1180
After 750 820 1020 790 1040 1200 4. (25 points) A company Claims that 20% of its candies are green, 40% are red,
and 40% are yellow. To test this a simple random sample of 300 candies is
obtained. Of them 70 were green, 130 were red and 100 — yellow, At the 0.025
level of significance test company’s claim. 5. (25 points) Consider the following set of paired x, y data.
x 1 2 3 5
y 2 4 6 8 (a) (10 points) At the 0.05 level of significance test the claim that there is significant linear correlation between x and y.
(b) (15 points) Find the equation of the regression line for the data and the best predicted value for y when x = 4 6. (25 points) Independent simple random samples of prices ofa pound of meat are
taken from different stores 0f3 grocery chains. The table that follows gives their weights
in pounds. Use ANOVA with a signiﬁcance level of 0.05 to test the claim that all 3 chains price their meat with the same mean price. Chain 1 Chain 2 Chain 3
2 3 5 3 4 5
2 5 6
5 6 7 ...
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 Spring '11
 NA
 Statistics, Simple random sample, Significance test

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