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Step 1:
I'll solve these problems step by step, following the precise LaTeX formatting guidelines:

Problem 17: SSE (Sum of Squared Errors) Relationship

Step 2:
: Understand SSE and SST

- SST (Total Sum of Squares) represents total variance in the dependent variable - SSE (Sum of Squared Errors) represents unexplained variance

Step 3:
: Key Property of SSE

- SSE is always non-negative - SSE cannot be larger than SST - SSE can be zero only if the regression line perfectly fits all data points

Final Answer

Problem 18: Regression Equation Analysis Step 1: Interpret the Equation \bar{Y} = 50,000 - 8X - \bar{Y} represents predicted sales - For each $\$1$ increase in price (X), sales decrease by $\$8$ Step 2: Calculation Example - If price increases by $\$1$, sales will decrease by $\$8$ Problem 19: Slope Calculation Step 1: Slope Formula \text{Slope} = \frac{n\sum{xy} - \sum{x}\sum{y}}{n\sum{x^{2}} - (\sum{x})^{2}} Step 2: Calculate Components - \sum{x} = 3 + 5 + 8 + 12 = 28 - \sum{y} = 20 + 25 + 32 + 43 = 120 - \sum{xy} = (3 \times 20) + (5 \times 25) + (8 \times 32) + (12 \times 43) Step 3: Detailed Calculation - After careful computation, the slope is 2.5435 Problem 20: Y-Intercept Calculation Step 1: Y-Intercept Formula b_{0} = \bar{y} - b_{1}\bar{x} Step 2: Calculate Mean Values - \bar{x} = \frac{28}{4} = 7 - \bar{y} = \frac{120}{4} = 30 Step 3: Use Slope from Previous Problem - Slope b_{1} = 2.5435 - b_{0} = 30 - (2.5435 \times 7) = 12.1965