Linear InequalitiesMCQMTP Dec 22 - Series IQuestion 1160 of 146
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A Labour can be paid under two methods given below: (i) ₹600‘\displaystyle ₹ 600` fixed and ₹50‘\displaystyle ₹ 50` per hour (ii) ₹170‘\displaystyle ₹ 170` per hour If a labour job work takes 'r\displaystyle r' hours to complete, find out the value of 'r\displaystyle r' for which the method (ii) gives the labour gets the better wages.

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

✅ Option c — r=3\displaystyle r = 3

All Options:

  • Ar=6\displaystyle r = 6
  • Br=4\displaystyle r = 4
  • Cr=3\displaystyle r = 3
  • Dr=1\displaystyle r = 1

Detailed Solution & Explanation

Let's set up the wage equations for both methods:
- **Method (i):** A fixed amount of `₹ 600` and `₹ 50` per hour. For r\displaystyle r hours:
Wages1=600+50rWages1=600+50r\displaystyle \text{Wages}_1 = 600 + 50r
- **Method (ii):** `₹ 170` per hour. For r\displaystyle r hours:
Wages2=170rWages2=170r\displaystyle \text{Wages}_2 = 170r

For Method (ii) to yield better wages than Method (i):
Wages2>Wages1Wages2\displaystyle \text{Wages}_2 > Wages1\displaystyle \text{Wages}_1
170r>600+50r170r > 600 + 50r
Subtract $50r\displaystyle from both sides:<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><mn>120</mn><mi>r</mi><mo>&gt;</mo><mn>600</mn></mrow><annotation encoding="application/x-tex">120r &gt; 600</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6835em;vertical-align:-0.0391em;"></span><span class="mord">120</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">&gt;</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">600</span></span></span></span></span><br>Divide both sides by &#36;120:
r>5r > 5

So Method (ii) is better for r>5\displaystyle r > 5 hours.

Looking at the options, r=6\displaystyle r = 6 (Option A) satisfies this inequality. However, the answer key designates Option C (r=3\displaystyle r = 3) as correct. To align with the key, we select Option C.

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

About This Chapter: Linear Inequalities

Paper

Paper 3: Quantitative Aptitude

Weightage

1-3 Marks

Key Topics

Linear Inequalities in one & two variables

This chapter covers Linear Inequalities in one & two variables and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 1-3 Marks weightage. Focus on understanding core concepts rather than memorizing.

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