{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Practice Midterm

# Practice Midterm - GEORGE WASHINGTON UNIVERSITY Department...

This preview shows pages 1–2. Sign up to view the full content.

GEORGE WASHINGTON UNIVERSITY Department of Statistics STAT 118, Section 10, Fall 2009 Practice Midterm 1. Express the following system of equations in matrix form. y 1 = β 0 + 8 β 1 + 4 β 2 + 1 y 2 = β 0 + 11 β 1 + 5 β 2 + 2 y 3 = β 0 + β 1 + β 2 + 3 y 4 = β 0 + 7 β 1 + 3 2. Given the matrix X and vector y , find ( X X ) - 1 , X y and ( X X ) - 1 X y . X= 2 3 y = 11 1 0 5 3 -1 7 0 2 8 4 5 15 0 1 4 3. Sometimes additives are used to boost the mileage of cars. An automechanic wants to study the effect of a particular additive on mileage. She took a random sample of 11 cars (of similar type) and observed the mileage(mpg)( Y ) obtained for different amounts of additive used(in ml/G)( X ) under similar driving conditions. The results of the study and partial SAS output is reproduced below. Additive amount( x ) 10 13 8 18 15 20 10 5 22 16 6 Mileage(mpg) ( y ) 27.5 28.8 28.1 33.5 29.6 32.6 28.1 26.5 34.9 31.7 24.9 Dependent Variable: mpg Analysis of Variance Sum of Mean Source DF Squares Square F Value Model 1 -------- 89.72299 ------- Error -- 8.20428 -------- Corrected Total -- 97.92727 Root MSE -------- R-Square 0.9162 Dependent Mean 29.65455 Adj R-Sq 0.9069 Parameter Estimates Parameter Variable

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}