The value of $\log_{.01}(1000)$ is
Aptitude
Logarithm
Difficulty: Medium
Choose an option
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A$\frac{1}{3}$
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B$-\frac{1}{3}$
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C$\frac{3}{2}$
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D$-\frac{3}{2}$
Answer
Correct Answer: $-\frac{3}{2}$
Explanation
Concept & Formula
When both the base and the argument can be expressed as powers of the same number (e.g., $10$), use the base and argument exponent rule:
$$ \log_{a^m} (a^n) = \frac{n}{m} $$
Step-by-Step Solution
* **Given:** Evaluate $\log_{.01}(1000)$.
* **Calculation:** Express both the base ($0.01$) and the argument ($1000$) as powers of $10$.
* For the base: $0.01 = \frac{1}{100} = 10^{-2}$.
* For the argument: $1000 = 10^3$.
* Substitute these into the logarithm:
$$ \log_{10^{-2}} (10^3) $$
* Apply the property $\log_{a^m} (b^n) = \frac{n}{m} \log_a b$:
$$ \frac{3}{-2} \log_{10} 10 $$
* Since $\log_{10} 10 = 1$, the expression simplifies to:
$$ -\frac{3}{2} $$
Exam Strategy & Shortcut
Don't write out the formulas. Just look at the powers of $10$. The base $.01$ is $-2$ power. The argument $1000$ is $+3$ power. The answer is always (power of argument) / (power of base) $\rightarrow 3 / -2 = -3/2$.
Common Pitfall
Students often invert the fraction, arriving at $-2/3$ instead of $-3/2$. Always remember it is the argument's exponent divided by the base's exponent, not the other way around.
Final Answer
**Therefore, the correct answer is -\frac{3}{2}.**