EXAM 3solutions1

# EXAM 3solutions1 - Here are my answers Change everything...

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Here are my answers: Change everything you see, I don’t want anybody to get caught cheating. Problem # 1 What is the proceedure used to find the equations from which the parameters a & b of the 'least-squares' line y = a + bx are found? Answer: First of all, a sample of data of a certain population is collected and looked at point by point. A process called Linear regression is used to obtain the linear regression equation y=a+bx. In this process the regression curve approximates the mean value of the data. The constants a and b are determined by solving simultaneously the equations: 2 y an b x xy a x b x = + = + Where a is the y-intercept, and b is the slope of the resulting linear equation. Solving them for the data we get: 1 1 n n i i i i y b x a n = = - = 1 1 1 2 2 1 1 ( ) n n n i i i i i i i n n i i i i n x y x y b n x x = = = = = - = - � �

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Question 2- In the past the weight of a given production item was 40 ounces with a standard deviation of .32 ounce. A random sample of 20 items showed a standared deviation of .25. Is the
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