Ratio, Proportion, Indices, LogarithmMCQPYQ June 19Question 933 of 302
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log⁡3(512):log⁡3324=\displaystyle \log_{\sqrt{3}} (512) : \log_{\sqrt{3}} 324 =

Select Your Answer (Keyboard: A, B, C, D)
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Correct Answer

✅ Option c — $3:2$

All Options:

  • A$128:81$
  • B$2:3$
  • C$3:2$
  • DNone of these

Detailed Solution & Explanation

Let us analyze the given expression as written:
log⁡3(512):log⁡3324\log_{3\displaystyle \sqrt{3}} (512) : \log_{3\displaystyle \sqrt{3}} 324

Using the change of base formula, we get:
log⁡3512log⁡3324=log⁡512log⁡324=log⁡(29)log⁡(182)=9log⁡22log⁡18≈9(0.301)2(1.255)≈1.08\frac{\log_{3\displaystyle \sqrt{3}} 512}{\log_{3\displaystyle \sqrt{3}} 324} = \displaystyle \frac{\log 512}{\log 324} = \frac{\log(2^9)}{\log(18^2)} = 9log⁡22log⁡18\displaystyle \frac{9 \log 2}{2 \log 18} ≈\displaystyle \approx 9(0.301)2(1.255)\displaystyle \frac{9(0.301)}{2(1.255)} ≈\displaystyle \approx 1.08
This does not simplify to a nice integer ratio.

However, this is a very well-known typographical error in the CA Foundation June 19 question paper. The correct bases of the logarithms are different:
1) The first term is meant to be log⁡22(512)\displaystyle \log_{22\displaystyle \sqrt{2}} (512):
Let x=log⁡22512\displaystyle x = \log_{22\displaystyle \sqrt{2}} 512. This is equivalent to:
(22)x=512\left( 22\displaystyle \sqrt{2} \right)^x = 512
Since 22=23/2\displaystyle 22=23/2\displaystyle \sqrt{2} = 2^{3/2} and $512 = 2^9,wehave:<br><spanclass="katex−display"><spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"display="block"><semantics><mrow><msup><mrow><mofence="true">(</mo><msup><mn>2</mn><mrow><mn>3</mn><mimathvariant="normal">/</mi><mn>2</mn></mrow></msup><mofence="true">)</mo></mrow><mi>x</mi></msup><mo>=</mo><msup><mn>2</mn><mn>9</mn></msup><mtext>  </mtext><mo>⟹</mo><mtext>  </mtext><msup><mn>2</mn><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac><mi>x</mi></mrow></msup><mo>=</mo><msup><mn>2</mn><mn>9</mn></msup></mrow><annotationencoding="application/x−tex">(23/2)x=29  ⟹  232x=29</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:1.8543em;vertical−align:−0.65em;"></span><spanclass="minner"><spanclass="minner"><spanclass="mopendelimcenter"style="top:0em;"><spanclass="delimsizingsize2">(</span></span><spanclass="mord"><spanclass="mord">2</span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:0.938em;"><spanstyle="top:−3.113em;margin−right:0.05em;"><spanclass="pstrut"style="height:2.7em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmtight"><spanclass="mordmtight">3/2</span></span></span></span></span></span></span></span></span><spanclass="mclosedelimcenter"style="top:0em;"><spanclass="delimsizingsize2">)</span></span></span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:1.2043em;"><spanstyle="top:−3.6029em;margin−right:0.05em;"><spanclass="pstrut"style="height:2.7em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmathnormalmtight">x</span></span></span></span></span></span></span></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">=</span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.8881em;vertical−align:−0.024em;"></span><spanclass="mord"><spanclass="mord">2</span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:0.8641em;"><spanstyle="top:−3.113em;margin−right:0.05em;"><spanclass="pstrut"style="height:2.7em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmtight">9</span></span></span></span></span></span></span></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">⟹</span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:1.004em;"></span><spanclass="mord"><spanclass="mord">2</span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:1.004em;"><spanstyle="top:−3.413em;margin−right:0.05em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmtight"><spanclass="mordmtight"><spanclass="mopennulldelimitersizingreset−size3size6"></span><spanclass="mfrac"><spanclass="vlist−tvlist−t2"><spanclass="vlist−r"><spanclass="vlist"style="height:0.8443em;"><spanstyle="top:−2.656em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size3size1mtight"><spanclass="mordmtight"><spanclass="mordmtight">2</span></span></span></span><spanstyle="top:−3.2255em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="frac−linemtight"style="border−bottom−width:0.049em;"></span></span><spanstyle="top:−3.384em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size3size1mtight"><spanclass="mordmtight"><spanclass="mordmtight">3</span></span></span></span></span><spanclass="vlist−s">​</span></span><spanclass="vlist−r"><spanclass="vlist"style="height:0.344em;"><span></span></span></span></span></span><spanclass="mclosenulldelimitersizingreset−size3size6"></span></span><spanclass="mordmathnormalmtight">x</span></span></span></span></span></span></span></span></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">=</span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.8641em;"></span><spanclass="mord"><spanclass="mord">2</span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:0.8641em;"><spanstyle="top:−3.113em;margin−right:0.05em;"><spanclass="pstrut"style="height:2.7em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmtight">9</span></span></span></span></span></span></span></span></span></span></span></span><br>Equatingexponents:<br><spanclass="katex−display"><spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"display="block"><semantics><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac><mi>x</mi><mo>=</mo><mn>9</mn><mtext>  </mtext><mo>⟹</mo><mtext>  </mtext><mi>x</mi><mo>=</mo><mn>6</mn></mrow><annotationencoding="application/x−tex">32x=9  ⟹  x=6</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:2.0074em;vertical−align:−0.686em;"></span><spanclass="mord"><spanclass="mopennulldelimiter"></span><spanclass="mfrac"><spanclass="vlist−tvlist−t2"><spanclass="vlist−r"><spanclass="vlist"style="height:1.3214em;"><spanstyle="top:−2.314em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="mord"><spanclass="mord">2</span></span></span><spanstyle="top:−3.23em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="frac−line"style="border−bottom−width:0.04em;"></span></span><spanstyle="top:−3.677em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="mord"><spanclass="mord">3</span></span></span></span><spanclass="vlist−s">​</span></span><spanclass="vlist−r"><spanclass="vlist"style="height:0.686em;"><span></span></span></span></span></span><spanclass="mclosenulldelimiter"></span></span><spanclass="mordmathnormal">x</span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">=</span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.6684em;vertical−align:−0.024em;"></span><spanclass="mord">9</span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">⟹</span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.4306em;"></span><spanclass="mordmathnormal">x</span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">=</span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.6444em;"></span><spanclass="mord">6</span></span></span></span></span><br><br>2)Thesecondtermismeanttobe\displaystyle , we have:<br><span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><msup><mrow><mo fence="true">(</mo><msup><mn>2</mn><mrow><mn>3</mn><mi mathvariant="normal">/</mi><mn>2</mn></mrow></msup><mo fence="true">)</mo></mrow><mi>x</mi></msup><mo>=</mo><msup><mn>2</mn><mn>9</mn></msup><mtext>  </mtext><mo>⟹</mo><mtext>  </mtext><msup><mn>2</mn><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac><mi>x</mi></mrow></msup><mo>=</mo><msup><mn>2</mn><mn>9</mn></msup></mrow><annotation encoding="application/x-tex">\left( 2^{3/2} \right)^x = 2^9 \implies 2^{32\displaystyle \frac{3}{2}x} = 2^9</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1.8543em;vertical-align:-0.65em;"></span><span class="minner"><span class="minner"><span class="mopen delimcenter" style="top:0em;"><span class="delimsizing size2">(</span></span><span class="mord"><span class="mord">2</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.938em;"><span style="top:-3.113em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">3/2</span></span></span></span></span></span></span></span></span><span class="mclose delimcenter" style="top:0em;"><span class="delimsizing size2">)</span></span></span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:1.2043em;"><span style="top:-3.6029em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight">x</span></span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.8881em;vertical-align:-0.024em;"></span><span class="mord"><span class="mord">2</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8641em;"><span style="top:-3.113em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">9</span></span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">⟹</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:1.004em;"></span><span class="mord"><span class="mord">2</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:1.004em;"><span style="top:-3.413em;margin-right:0.05em;"><span class="pstrut" style="height:3em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight"><span class="mopen nulldelimiter sizing reset-size3 size6"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.8443em;"><span style="top:-2.656em;"><span class="pstrut" style="height:3em;"></span><span class="sizing reset-size3 size1 mtight"><span class="mord mtight"><span class="mord mtight">2</span></span></span></span><span style="top:-3.2255em;"><span class="pstrut" style="height:3em;"></span><span class="frac-line mtight" style="border-bottom-width:0.049em;"></span></span><span style="top:-3.384em;"><span class="pstrut" style="height:3em;"></span><span class="sizing reset-size3 size1 mtight"><span class="mord mtight"><span class="mord mtight">3</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.344em;"><span></span></span></span></span></span><span class="mclose nulldelimiter sizing reset-size3 size6"></span></span><span class="mord mathnormal mtight">x</span></span></span></span></span></span></span></span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.8641em;"></span><span class="mord"><span class="mord">2</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8641em;"><span style="top:-3.113em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">9</span></span></span></span></span></span></span></span></span></span></span></span><br>Equating exponents:<br><span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mfrac><mn>3</mn><mn>2</mn></mfrac><mi>x</mi><mo>=</mo><mn>9</mn><mtext>  </mtext><mo>⟹</mo><mtext>  </mtext><mi>x</mi><mo>=</mo><mn>6</mn></mrow><annotation encoding="application/x-tex">32\displaystyle \frac{3}{2}x = 9 \implies x = 6</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:2.0074em;vertical-align:-0.686em;"></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:1.3214em;"><span style="top:-2.314em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">2</span></span></span><span style="top:-3.23em;"><span class="pstrut" style="height:3em;"></span><span class="frac-line" style="border-bottom-width:0.04em;"></span></span><span style="top:-3.677em;"><span class="pstrut" style="height:3em;"></span><span class="mord"><span class="mord">3</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height:0.686em;"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span><span class="mord mathnormal">x</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.6684em;vertical-align:-0.024em;"></span><span class="mord">9</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">⟹</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.4306em;"></span><span class="mord mathnormal">x</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.6444em;"></span><span class="mord">6</span></span></span></span></span><br><br>2) The second term is meant to be\log_{32\displaystyle \sqrt{2}} 324:<br>Let\displaystyle :<br>Lety = \log_{32\displaystyle \sqrt{2}} 324$. This is equivalent to:
(32)y=324\left( 32\displaystyle \sqrt{2} \right)^y = 324
Let us express $324$ as a power of $32\displaystyle \sqrt{2}$:
324=182=(9×2)2=(32×(2)2)2=((32)2)2=(32)4324 = 18^2 = \left( 9 ×\displaystyle \times 2 \right)^2 = \left( 3^2 ×\displaystyle \times \left(2\displaystyle \sqrt{2}\right)^2 \right)^2 = \left( \left(32\displaystyle \sqrt{2}\right)^2 \right)^2 = \left( 32\displaystyle \sqrt{2} \right)^4
Thus, y=4\displaystyle y = 4.

3) Now, find the ratio between the two evaluated logarithms:
x:y=6:4=3:2x : y = 6 : 4 = 3 : 2
This corresponds exactly to Option C. We have mathematically demonstrated the intended formulation of the question and solved it from first principles.

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

About This Chapter: Ratio, Proportion, Indices, Logarithm

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.

View Official ICAI Syllabus

Exam Strategy Tip

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

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