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%%%%%%%% PREAMBLE\documentclass{article}% Extra packages for graphics, header control, good math typesetting, and margin% control:%\usepackage{amsmath}%My default package%\usepackage{graphicx}%needed to insert figures\usepackage{graphicx, amsmath}%,\usepackage[usenames]{color}%for colored text\usepackage{hyperref}%needed for footnotes, hyperlinks, etc. (must be placed AFTERall the other packages)\hypersetup{colorlinks,%this will make the links the text instead of putting anugly box around the linkscitecolor=blue,%filecolor=blue,%linkcolor=blue,%urlcolor=blue}\definecolor{gray}{gray}{0.95}%defining gray\definecolor{orange}{rgb}{.7,0.5,0}%the last curly brace tells you how much of red,green and blue\definecolor{orange2}{cmyk}{0,0.5,1,0}%another orange%\usepackage{multirow}% \usepackage{pxfonts}%\numberwithin{equation}{section}% Lengths and margins: you're not supposed to monkey around with these in LaTeX,% but default margins waste a lot of paper. For readability, leave lots of space% on the left and right, but feel free to cut down blank space at the top and% bottom of the page.%\usepackage{amsfonts, amsmath, amsthm, graphicx}%\usepackage{setspace}% The amssymb package provides various useful mathematical symbols%\usepackage{amssymb}%\usepackage{harvard}%\usepackage[none]{hyphenat}%\sloppy%\usepackage[ngerman]{babel}%\usepackage[latin1]{inputenc}%\geometry{ left = 1.75in, right = 1.75in, top = 1in, bottom = 1in }%\geometry{ left = 1in, right = 1in, top = 1in, bottom = 1in } %this is for one-inch margins instead of the normal LaTeX margins% Headers and footers with FANCYHDR, a package which provides some useful extra% commands. Note that l, r and c denote left, right and center. The% \headsep line contrals space between your header and the first bit of actual% text on the page. The \headrulewidth line controls the thickness of the line% under your header. Set this to 0 (by un-commenting the line below) if you% don't want a line there.%\newenvironment{packed_enum}{%\begin{itemize}%\setlength{\itemsep}{1pt}
%\setlength{\parskip}{0pt}%\setlength{\parsep}{0pt}%}{\end{itemize}}%\pagestyle{fancy}%\setlength{\headsep}{.5in}%\renewcommand{\headrulewidth}{.25pt}%\lhead{\footnotesize Econ 244}%\chead{Alex, James, Teferi, Sebastian, Deza}%\rhead{\footnotesize February 27th, 2009}%\lfoot{}%\cfoot{\footnotesize Page \thepage}%\rfoot{}% To avoid typing long expressions many times, define your own commands. (In some% cases, LaTeX may already have definitions for the names you've chosen, in which% case you need to re-define them -- this is the difference between %%%%\newcommand% and \renewcommand.)%\setstretch{1.35}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% END OFPREAMBLE\begin{document}%\begin{flushright}%Name%\end{flushright}%\begin{center}%title%\end{center}%BEGIN NORMAL WORD PAPER HERE:%%%%%%%%%%%%%%%%%%%lastquestion on final%%%%%%%%%%%%%%%%%%%%%%%%%%%\begin{enumerate}\item[4.] Urban travel times and distances are important factors in the analysis oftraffic flowpatterns. A traffic engineer in Los Angeles obtained the following data from areafreeways.x = miles traveled and y = time in minutes to travel x miles in an automobile.\\\begin{table}[htbp]\caption{}\begin{center}\begin{tabular}{|l|r|r|r|r|r|r|r|r|}\hline\textbf{X} & 5 & 9 & 3 & 11 & 20 & 15 & 12 & 25 \\ \hline\textbf{Y} & 9 & 13 & 6 & 16 & 28 & 21 & 16 & 31 \\ \hline\end{tabular}\end{center}\label{}\end{table}\\\begin{enumerate}%%%%%%%%%%%%%%%%%%%%%part(a.)%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\item(5 points) Calculate $\sum{x}, \sum{y}, \sum{x^2}, \sum{y^2}, \sum{xy},\bar{x}, \bar{y}$ and draw the scatter diagram.\\\textit{Comments:} so next is just the algorithm we followed in class(calc. the
above quantities, draw the scatter diagram, show that you can represent the data bya line by making sure r $\geq$ critical value on page 600 of the book, find theequation of $\hat{y}$, draw $\hat{y}$, given an x-value give the corresponding y-value, use a hypothesis test to see if the <i>population</i> can be correlated by aline, and finally, find the confindence interval of y values for a given x value(part (g.))\\\begin{table}[htbp]\caption{}\begin{center}\begin{tabular}{cccccccccc}& $x$ & & $y$ & & $x^{2}$ & & $y^{2}$ & & $xy$ \\& 5 & & 9 & & 25 & & 81 & & 45 \\& 9 & & 13 & & 81 & & 169 & & 117 \\& 3 & & 6 & & 9 & & 36 & & 18 \\& 11 & & 16 & & 121 & & 256 & & 176 \\& 20 & & 28 & & 400 & & 784 & & 560 \\& 15 & & 21 & & 225 & & 441 & & 315 \\& 12 & & 16 & & 144 & & 256 & & 192 \\& 25 & & 31 & & 625 & & 961 & & 775 \\$\sum{x}$= & 100 & $\sum{y}$= & 140 & $\sum{x^{2}}$= & 1630 & $\sum{y^{2}}$= & 2984& $\sum{xy}$= & 2198 \\\end{tabular}\end{center}\label{}\end{table}\\$\bar{x} = \frac{\sum{x}}{n} = \frac{100}{8} = 12.5 $\\$\bar{y} = \frac{\sum{y}}{n}= \frac{140}{8}=17.5$\\For the scatter diagram see \hyperref[scatter]{the appendix}\\%the first bracket isthe name of the label%I need this because otherwise the following text in the next part of the problemcomes before the graph.%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%___________________________partb_______________________________________%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\item (5 points) Show analytically that you can correlate the data from this sampleby a line with $\alpha=0.05$\\\begin{align*}%align with the star means that it won't have a numberr &= \frac{n\sum{xy}-\sum{x}\sum{y}}{\sqrt{n\sum{x^{2}}-(\sum{x})^{2}}\sqrt{n\sum{y^{2}}-(\sum{y})^{2}}}\\&=\frac{8(2198)-(100)(140)}{\sqrt{8(1630)-100^{2}}\sqrt{8(2984)-140^{2}}}\\&=\frac{3584}{\sqrt{3040}\sqrt{4272}}\\&= 0.9945\end{align*}Since $r=0.9945 \leq 0.71 = $\text{critical value on page}600(\hyperref[criticalvalue]{see appendix}), we can correlate the data by a line.\item (5 points)Find the equation of the line that best correlates the data fromthe sample\\\textit{Comments: }So for this part we also follow the algorithm for the class(i.e., find $b$, then find $a$, then find $\hat{y}$)\\\begin{align*}b &=\frac{n\sum{xy} -\sum{x}\sum{y}}{n\sum{x^{2}-(\sum{x})^{2}}}=\frac{3584}{3040}=1.18\\a &=\bar{y}-b\bar{x}=17.5-(1.18)(12.5)=2.76\\\hat{y} &=a + bx\\\hat{y} &= 2.76 + 1.18x
\end{align*}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%___________________________partd_______________________________________%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\item (5 points) Draw the line from part (c.) on the scatter plot.\\\textit{Comments:} just pick two $x$'s and find the corresponding $y$-values butplugging in the $x$-values into the $\hat{y}$ formula. For instance, I picked 5 and25 for my $x$ values, but you can pretty much pick which ever values you'd like.\\\begin{table}[htbp]\caption{}\begin{tabular}{|c|c|}\hline$x$ & $y$ \\ \hline5 & 8.7 \\ \hline25 & 32.2 \\ \hline\end{tabular}\label{}\end{table}\begin{align*}2.76 + 1.18(5) &= 8.7\\2.76 + 1.18(25) &= 32.2\end{align*}Then just plot these points on the graph\\%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%___________________________parte_______________________________________%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\item (5 points) Predict time in minutes to travel 31 miles on the Freeway\\\begin{align*}x &= 31\\\hat{y} &= 2.76 + 1.18(31)\\&= 39.3 minutes\end{align*}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%___________________________partf_______________________________________%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\item (15 points) Test hypothesis about the population correlation coefficient with$\alpha = 0.05$.\begin{itemize}\item State the null and alternate hypothesis\\\begin{align*}H_{0} &: \phi = 0\\H_{1} &; \phi > 0\end{align*}\item Compute sample test statistics\\d.f. = n-2 = 8-2 = 6\begin{align*}t &= \frac{r\sqrt{n-2}}{\sqrt{1-r^{2}}}\\&=\frac{.995\sqrt{8-2}}{\sqrt{1-(.995)^{2}}}\\&= \frac{.995\sqrt{6}}{\sqrt{1-(.995)^2}}\\&= 23.3

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