Math Problem Statement

You want to calculate the area of your dorm room which is in a rectangular shape. You measure the length and the width of the room as L = 6.5 ± 0.1 m, W = 4.2 ± 0.1 m. What is the absolute error in the area in m² units?

Solution

To solve the problem of finding the absolute error in the area of the dorm room:

Problem Setup

The area AA of a rectangular room is calculated as: A=LWA = L \cdot W where:

  • L=6.5±0.1mL = 6.5 \pm 0.1 \, \text{m} (length with uncertainty),
  • W=4.2±0.1mW = 4.2 \pm 0.1 \, \text{m} (width with uncertainty).

Formula for Absolute Error in Area

The absolute error in AA is given by: ΔA=(ΔLW)+(LΔW)\Delta A = \left( \Delta L \cdot W \right) + \left( L \cdot \Delta W \right) where ΔL=0.1m\Delta L = 0.1 \, \text{m} and ΔW=0.1m\Delta W = 0.1 \, \text{m}.

Calculation

  1. Compute the area: A=LW=6.54.2=27.3m2A = L \cdot W = 6.5 \cdot 4.2 = 27.3 \, \text{m}^2

  2. Compute the absolute error: ΔA=(0.14.2)+(6.50.1)\Delta A = (0.1 \cdot 4.2) + (6.5 \cdot 0.1) ΔA=0.42+0.65=1.07m2\Delta A = 0.42 + 0.65 = 1.07 \, \text{m}^2

Final Result

  • The area of the dorm room is 27.3m227.3 \, \text{m}^2.
  • The absolute error in the area is ΔA=1.07m2\Delta A = 1.07 \, \text{m}^2.

Would you like a more detailed explanation of any step? Let me know!


Here are 5 related questions for practice:

  1. How would the error change if ΔL=0.2m\Delta L = 0.2 \, \text{m}?
  2. What is the percentage error in the area?
  3. How is relative error in area calculated for this problem?
  4. What would happen to the area if both LL and WW increased by their uncertainties?
  5. How can you reduce measurement errors in determining the area of a rectangular space?

Tip: Always report uncertainties with your measurements to ensure accuracy and precision in calculations!

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Math Problem Analysis

Mathematical Concepts

Error Analysis
Uncertainty Propagation
Geometry of Rectangles

Formulas

Area of rectangle: A = L × W
Absolute error in area: ΔA = (ΔL × W) + (L × ΔW)

Theorems

Uncertainty propagation rule for multiplication

Suitable Grade Level

Grades 9-12