Logarithm example 1
Problem
Solve the equation 2t = 25 for t.
Solution
First method. Take logs of both sides to base 2 and obtain t = log2 25
Solution
Second method. Take logs of both sides to base b and obtain
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logb 25 |
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Use b = 10 or b = e on your calculator to get t ' 4. 6439.
Steve Sugden (Bond University) |
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31 August 2011 |
14 / 15 |
Logarithm example 2
Problem
Compound interest. How long to double your money at 10% compound interest?
Solution
We have F = P (1 + r )n where P is present value (principal), F is future value, r is the rate of interest, and n is the number of periods of compounding. Without loss of generality, we may take P = 1 and F = 2, and so write:
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log 2 |
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' 7.2725 |
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log 1.1 |
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Steve Sugden (Bond University) |
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31 August 2011 15 / 15 |
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