6.2.6

Compund Interest

Test yourself

Compound Interest

In summer, the number of ants in a colony increases by 20% each day. On the first day there are 10,000 ants. How many days until the colony numbers more than 30,000?

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The formula for compound interest

  • N is the number of ants
  • n is the number of days passed
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Answer

  • This is the first day we are over 30 000 so the answer is 7 days.
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Number of ants per hour

  • By using the rule for raising a power to another power, we can convert the multiplier for the growth after nn days into one that shows the growth every hour
  • This way we see that there is a 0.8% increase in the number of ants every hour.

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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