Math Problem Statement

The edge of a cube was found to be 15 cm with a possible error in measurement of 0.1 cm. Use differentials to estimate the maximum possible error, relative error, and percentage error in computing the volume of the cube and the surface area of the cube.

Solution

To solve this problem, let’s break down each part and calculate the required values using differentials.

Given:

  • Edge length of the cube, x=15x = 15 cm.
  • Possible error in measurement, dx=0.1dx = 0.1 cm.

We need to find:

  1. The maximum possible error, relative error, and percentage error in computing:
    • (a) the volume of the cube.
    • (b) the surface area of the cube.

(a) Volume of the Cube

The volume VV of a cube with edge length xx is given by: V=x3V = x^3

1. Differential of Volume

To estimate the maximum possible error in the volume, we use the differential: dV=3x2dxdV = 3x^2 \cdot dx

Plugging in the values: dV=3×(15)2×0.1=3×225×0.1=67.5cm3dV = 3 \times (15)^2 \times 0.1 = 3 \times 225 \times 0.1 = 67.5 \, \text{cm}^3

So, the maximum possible error in volume is 67.5cm367.5 \, \text{cm}^3.

2. Relative Error in Volume

The relative error is given by: Relative Error=dVV\text{Relative Error} = \frac{dV}{V}

Calculating VV with x=15x = 15: V=153=3375cm3V = 15^3 = 3375 \, \text{cm}^3

Then, Relative Error=67.533750.02\text{Relative Error} = \frac{67.5}{3375} \approx 0.02

So, the relative error in volume (rounded to four decimal places) is 0.02000.0200.

3. Percentage Error in Volume

The percentage error is simply the relative error multiplied by 100: [ \text{Percentage Error}

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Math Problem Analysis

Mathematical Concepts

Differentials
Error Analysis
Volume and Surface Area of Cube

Formulas

Volume of a cube, V = x^3
Differential of volume, dV = 3x^2 * dx
Surface area of a cube, A = 6x^2
Differential of surface area, dA = 12x * dx

Theorems

Differentiation

Suitable Grade Level

Grades 11-12