EP STATISTICS F/BUS.+ECON.-ACCESS 18 WK
13th Edition
ISBN: 9780135960912
Author: MCCLAVE
Publisher: PEARSON CO
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Textbook Question
Chapter 2.3, Problem 2.46ACB
Surface roughness of oil field pipe. Oil field pipes are internally coated in order to prevent corrosion. Researchers at the University of Louisiana, Lafayette, investigated the influence that coating may have on the surface roughness of oil field pipes (Anti-corrosion Methods and Materials, Vol. 50, 2003). A scanning probe instrument was used to measure the surface roughness of each in a sample of 20 sections of coated interior pipe The data (in micrometers) are provided in the table.
- a. Find and interpret the
mean of the sample. - b. Find and interpret the
median of the sample. - c. Which measure of
central tendency —the mean or the median—best describes the surface roughness of the sampled pipe sections? Explain.
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Trace metals in drinking water affect the flavor and an unusually high concentration can pose a
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surface water.
Bottom 0.430 0.266 0.567 0.531 0.707 0.716 0.651 0.589 0.469 0.723
Surface 0.415 0.238 0.390 0.410 0.605 0.609 0.632 0.523 0.411 0.612
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an attempt to develop a model of wine quality as judged by wine experts, data on alcohol content and wine quality was collected from variants of a particular wine. From a sample of 12wines, a model was created using the percentages of alcohol to predict wine quality. For those data, SR=18,671 and SST=27,382.Use this information to complete parts (a) through (c) below. Please complete part 3(B) ONLY.
Question content area bottom
Part 1
a. Determine the coefficient of determination,
r2,
and interpret its meaning.
r2=0.682
(Round to three decimal places as needed.)
Part 2
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It means that
68.2
of the variation in
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(Round to one decimal place as needed.)
Part 3
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SYX=
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The quality control engineer at Palmer Industries is interested in estimating the tensile strength of steel wire based on its outside diameter and the amount of molybdenum in the steel. As an experiment, she selected 25 pieces of wire, measured the outside diameters, and determined the molybdenum content. Then she measured the tensile strength of each piece. The results of the first four are recorded in the table.
Tensile Strength
Outside Diameter
Amount of Molybdenum
Place
(PSI ) Y
(mm) X1
(Units) X2
A
11
0.3
6
B
9
0.2
5
C
16
0.4
8
D
12
0.3
7
Using a statistical software package, the QC engineer determined the multiple regression equation to be Y’=-0.5+20X1+1X2.
a) Based on the equation, what is the estimated tensile strength of a steel wire having an outside diameter of .35 mm and 6.4 units of molybdenum?
b) Interpret the value of b1 in the equation.
Chapter 2 Solutions
EP STATISTICS F/BUS.+ECON.-ACCESS 18 WK
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