Ratio, Proportion, Indices, LogarithmPYQ Sep 24Question 810 of 305
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The ratio of income of A and B is 5:4\displaystyle 5:4 and their expenditure is 3:2\displaystyle 3:2. If at the end of the year each saves ₹1,600\displaystyle ₹1,600, then the income of A is:

Options

A₹3,600\displaystyle ₹3,600
B₹3,400\displaystyle ₹3,400
C₹4,000\displaystyle ₹4,000
D₹4,200\displaystyle ₹4,200
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Correct Answer

✅ Option c — ₹4,000\displaystyle ₹4,000

All Options:

  • A₹3,600\displaystyle ₹3,600
  • B₹3,400\displaystyle ₹3,400
  • C₹4,000\displaystyle ₹4,000
  • D₹4,200\displaystyle ₹4,200

Detailed Solution & Explanation

Let the incomes of A\displaystyle A and B\displaystyle B be 5x\displaystyle 5x and 4x\displaystyle 4x, and their expenditures be 3y\displaystyle 3y and 2y\displaystyle 2y respectively.
Each saves ₹1,600\displaystyle ₹1,600 at the end of the year:
5x−3y=1600(1)5x - 3y = 1600 \quad (1)
4x−2y=1600(2)4x - 2y = 1600 \quad (2)
From equation (2), dividing both sides by 2\displaystyle 2 gives:
2x−y=800  ⟹  y=2x−8002x - y = 800 \implies y = 2x - 800
Substitute this expression for y\displaystyle y into equation (1):
5x−3(2x−800)=16005x - 3(2x - 800) = 1600
5x−6x+2400=16005x - 6x + 2400 = 1600
−x=1600−2400-x = 1600 - 2400
−x=−800  ⟹  x=800-x = -800 \implies x = 800
The income of A\displaystyle A is:
Income of A=5x=5(800)=₹4,000\text{Income of A} = 5x = 5(800) = ₹4,000

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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