Math Problem Statement

You have a garden which measures 4.40 ± 0.46m long and 5.75 ± 0.44m wide. You determine the total area using A = L * W, what is the uncertainty value on this area?

Solution

To calculate the uncertainty in the area of the garden, given the lengths with their uncertainties, we follow this process:

Given:

  • Length (LL) = 4.40 ± 0.46 m
  • Width (WW) = 5.75 ± 0.44 m
  • Formula for area A=L×WA = L \times W

Step 1: Calculate the area AA

A=L×W=4.40×5.75=25.3m2A = L \times W = 4.40 \times 5.75 = 25.3 \, \text{m}^2

Step 2: Determine the fractional uncertainties

The fractional uncertainty for each dimension is calculated as the uncertainty divided by the value:

ΔLL=0.464.40=0.1045\frac{\Delta L}{L} = \frac{0.46}{4.40} = 0.1045 ΔWW=0.445.75=0.0765\frac{\Delta W}{W} = \frac{0.44}{5.75} = 0.0765

Step 3: Calculate the total fractional uncertainty for the area

For multiplication, the total fractional uncertainty is the sum of the fractional uncertainties of length and width:

ΔAA=ΔLL+ΔWW=0.1045+0.0765=0.181\frac{\Delta A}{A} = \frac{\Delta L}{L} + \frac{\Delta W}{W} = 0.1045 + 0.0765 = 0.181

Step 4: Calculate the absolute uncertainty in the area

Now, multiply the total fractional uncertainty by the area to get the absolute uncertainty:

ΔA=A×ΔAA=25.3×0.181=4.58m2\Delta A = A \times \frac{\Delta A}{A} = 25.3 \times 0.181 = 4.58 \, \text{m}^2

Final Answer:

The uncertainty in the area is 4.6 m² (rounded to two significant figures).

Would you like further clarification on any part of the calculation?


Here are 5 related questions you might find useful:

  1. How do you calculate uncertainty when adding or subtracting quantities?
  2. What is the difference between absolute and fractional uncertainty?
  3. How do uncertainties combine when multiplying or dividing more than two

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Math Problem Analysis

Mathematical Concepts

Uncertainty calculation
Area of a rectangle
Error propagation

Formulas

A = L * W
Fractional uncertainty: ΔA/A = ΔL/L + ΔW/W
Absolute uncertainty: ΔA = A * (ΔA/A)

Theorems

Propagation of uncertainties in multiplication

Suitable Grade Level

Grade 10-12