EquationsMCQPYQ June 19Question 1007 of 221
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A number consist of two digits such that the digit in one's place in thrice the digit in ten's place. If 36 be added then the digits are reversed. Find the number ____.

Chapter 2 Diagram

Options

A62
B26
C39
DNone of these
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Correct Answer

Option b26

All Options:

  • A62
  • B26
  • C39
  • DNone of these

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Detailed Solution & Explanation

Let the digit at ten's place be x\displaystyle x and the digit at one's place be y\displaystyle y.
According to the first condition, the digit in the one's place is thrice the digit in the ten's place:
y=3xy = 3x
The original number is 10x+y\displaystyle 10x + y.
When 36 is added to the number, the digits are reversed. The reversed number is 10y+x\displaystyle 10y + x.
According to the second condition:
(10x+y)+36=10y+x(10x + y) + 36 = 10y + x
Simplifying the equation:
10xx+y10y+36=010x - x + y - 10y + 36 = 0
9x9y+36=09x - 9y + 36 = 0
9(yx)=369(y - x) = 36
yx=4y - x = 4
Substitute y=3x\displaystyle y = 3x into this equation:
3xx=43x - x = 4
2x=4    x=22x = 4 \implies x = 2
Now, find y\displaystyle y:
y=3(2)=6y = 3(2) = 6
Therefore, the original number is:
10x+y=10(2)+6=2610x + y = 10(2) + 6 = 26
Hence, the correct number is 26.
**Correct Option: (b)**

About This Chapter: Equations

Paper

Paper 3: Quantitative Aptitude

Weightage

4-6 Marks

Key Topics

Linear, Quadratic and Cubic Equations

This chapter covers Linear, Quadratic and Cubic Equations and is part of Paper 3: Quantitative Aptitude in the CA Foundation exam.

View Official ICAI Syllabus

Exam Strategy Tip

This topic carries 4-6 Marks weightage. Focus on understanding core concepts rather than memorizing.

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