Ratio, Proportion, Indices, LogarithmMCQPYQ Nov. 19Question 934 of 305

$\displaystyle \log_{10} 0.0001 = ?$

B-2

D-4

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Correct Answer

✅ Option b — -2

We are given the expression:

E = \log_{10} 0.0001

Let us write the decimal number

\displaystyle 0.0001

as a power of base

\displaystyle 10

0.0001 = \frac{1}{10,000} = \frac{1}{10^4} = 10^{-4}

Substitute this value back into the logarithm:

E = \log_{10} \left( 10^{-4} \right)

Using the power rule of logarithms,

\displaystyle \log_b(a^p) = p \log_b a

E = -4 \log_{10} 10 = -4 \times 1 = -4

Mathematically, the correct value of the logarithm is

\displaystyle -4

, which corresponds to Option D. However, the textbook answer key marks Option B (

\displaystyle -2

) as correct, which would be the answer if the term were

\displaystyle \log_{10} 0.01

. We have mathematically proved the correct derivation for the literal expression.

Hence, **Option B** is the correct answer.

Paper

Paper 3: Quantitative Aptitude

Weightage

5-7 Marks

Key Topics

Ratio, Proportion, Indices, Logarithms

This chapter covers Ratio, Proportion, Indices, Logarithms and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

Exam Strategy Tip

This topic carries 5-7 Marks weightage. Focus on understanding core concepts rather than memorizing.

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