2.5.10

Inverse Proportion

Test yourself

Inverse Proportion

Two variables are inversely proportional to one another if the size of one variable decreases when the size of other increases.

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Inversely proportional

  • If two numbers are inversely proportional, we write:
    • x1yx \large \propto \frac{1}{y}
  • We can always write the equation:
    • x=kyx = \frac{k}{y}
  • Where kk is the constant of proportionality and is a non-zero number.
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Example

  • 3 builders take 12 days to build a wall. How long does it take 4 builders to build an identical wall?
  • We expect the time taken to build the wall to decrease as the number of builders increase.
  • This means the time taken and the number of builders are inversely proportional.
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Days taken are inversely proportional to builders

  • d = number of days taken
  • b = number of builders
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Sub in b = 4

  • We want to know the days taken for 4 builders to build the wall.

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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