ABC26GN2026 · Logarithms

Subject: General Aptitude · Chapter: Logarithms · Exam: · Marks: · Difficulty:

If $\log _{x} 4=0.4$, then the value of $x$ is
(a)1
(b)4
(c)16
(d)32
Answer
Answer (as printed): D
Explanation
$\log _{x} 4=0.4 \Leftrightarrow \log _{x} 4=\frac{4}{10}=\frac{2}{5} \Leftrightarrow x^{2 / 5}=4$ $\Leftrightarrow x=4^{5 / 2}=\left(2^{2}\right)^{5 / 2}$ $\Leftrightarrow x=2^{\left(2 \times \frac{5}{2}\right)}=2^{5} \Leftrightarrow x=32$.

Explanation as extracted from the printed page; notation may be imperfect.

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