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Unformatted text preview: STAT350 Final Spring 2007 (12 pts) 1. Multiple choice. No work needs to be shown here, you will not receive partial credit. (i) Correlation coefficient r between two variables x and y has the same meaning as the regression slope between x and y . (a) True (b) False (c) Insufficient information (d) Depends on data (ii) Given a sample, a regression line is fitted, for the fitted line y = a + bx , which of the following is true: (a) The line passes through the point (0 , 0) (b) The line passes through the point ( x, y ) (c) The line passes through (0 , a ) (d) None of the above (iii) Two events A and B , we know that P ( A ) = a , P ( B ) = b , P ( A B ) = c , then 1 ( a + b c ) is the probability of what event? (a) A B (b) A B c (c) A c B c (d) A c B (iv) Let x be the mean of a sample x 1 , x 2 , ..., x n , and let s be the standard deviation. Then what is the mean and standard deviation of x 1 + c, x 2 + c, ...., x n + c ? (a) x + c and s (b) x + c and s + c (c) x and s (d) x and s + c (8 pts) 2. For a continuous random variable x ( &lt; x &lt; ), we know that its density function is f ( x ). Denote the mean of x by x , now show that the variance of x is 1 integraltext - x 2 f ( x ) dx 2 x ....
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