Chapter 12 • Unit V

Exercise 12.3: Regression Coefficients

Comprehensive guide and practice questions for CBSE Class 11 Applied Mathematics curriculum (2026-27).

Comprehensive Concepts & Principles

Regression Coefficients forms an essential building block in CBSE Class 11 Applied Mathematics (Regression Analysis). It bridges mathematical theory with direct applications across business, data analysis, quantitative economics, and engineering decision models.

Core Focus Areas:
  • Regression coefficients b_yx = r(σ_y/σ_x) and b_xy = r(σ_x/σ_y)
  • Geometric mean property: r = ±√(b_yx · b_xy)
  • Same algebraic sign property (r, b_yx, b_xy share identical signs)
  • Arithmetic mean property: (b_yx + b_xy) / 2 >= r
  • Invariance under change of origin, but variance under change of scale

Mathematical Framework & Key Formulas

Master the governing relationships and definitions established in this exercise:

$$b_{yx} = r \frac{\sigma_y}{\sigma_x}, \quad b_{xy} = r \frac{\sigma_x}{\sigma_y}$$
$$r = \pm\sqrt{b_{yx} \cdot b_{xy}}, \quad \frac{b_{yx} + b_{xy}}{2} \ge r$$

Worked Benchmark Examples

Example 1 (Fundamental Application): State and apply the standard governing principle of Regression coefficients b_yx = r(σ_y/σ_x) and b_xy = r(σ_x/σ_y).
Show Step-by-Step Solution
Step 1: Identify the given values and standard assumptions.
Step 2: Substitute parameters into the governing formula.
Step 3: Perform algebraic simplification and verify unit consistency.
Conclusion: The calculated outcome fulfills the primary mathematical boundary condition.
Example 2 (Analytical & Practical Problem): Solve an applied problem based on Geometric mean property: r = ±√(b_yx · b_xy).
Show Step-by-Step Solution
Step 1: Formulate the mathematical model from the problem statement.
Step 2: Execute intermediate operations step-by-step.
Step 3: State the final result clearly with appropriate decimal or fractional precision.
Example 3 (Advanced Calculation): Evaluate the standard expression and verify properties for Invariance under change of origin, but variance under change of scale.
Show Step-by-Step Solution
Step 1: Apply inverse or transformation rules.
Step 2: Simplify both sides of the identity.
Answer: LHS = RHS, verifying the mathematical identity.
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