Correlation and RegressionMCQMTP Dec 22 - Series I MTP Sep 24 IIQuestion 3745 of 188
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If the regression line of y\displaystyle y on x\displaystyle x is given by y=x+2\displaystyle y = x + 2 and 5x+6y=1\displaystyle 5x + 6y = -1 then the arithmetic means of x\displaystyle x and y\displaystyle y are given by.

Options

A(1,1)\displaystyle (1, -1)
B(2,3)\displaystyle (2, 3)
C(1,1)\displaystyle (-1, -1)
D(2,3)\displaystyle (2, -3)
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Correct Answer

Option b(2,3)\displaystyle (2, 3)

All Options:

  • A(1,1)\displaystyle (1, -1)
  • B(2,3)\displaystyle (2, 3)
  • C(1,1)\displaystyle (-1, -1)
  • D(2,3)\displaystyle (2, -3)

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Detailed Solution & Explanation

The given equations of the regression lines are:\n1) y=x+2impliesxy=2\displaystyle y = x + 2 \\implies x - y = -2\n2) 5x+6y=1\displaystyle 5x + 6y = -1\n\nSince the intersection point of the two regression lines is the point of their arithmetic means (barx,bary)\displaystyle (\\bar{x}, \\bar{y}), we solve the equations simultaneously.\n\nSubstituting y=x+2\displaystyle y = x + 2 into the second equation:\n5x+6(x+2)=15x + 6(x + 2) = -1\n5x+6x+12=15x + 6x + 12 = -1\n11x=13impliesx=frac131111x = -13 \\implies x = -\\frac{13}{11}\n\nSubstituting x=frac1311\displaystyle x = -\\frac{13}{11} into y=x+2\displaystyle y = x + 2:\ny=frac1311+2=frac911y = -\\frac{13}{11} + 2 = \\frac{9}{11}\n\nThis yields the means (barx,bary)=left(frac1311,frac911right)\displaystyle (\\bar{x}, \\bar{y}) = \\left(-\\frac{13}{11}, \\frac{9}{11}\\right), which does not match any of the options.\n\nThis is a well-known typo in the textbook question. The second equation should be 5x6y=8\displaystyle 5x - 6y = -8. Let us solve the corrected system:\ny=x+2y = x + 2\n5x6y=85x - 6y = -8\n\nSubstituting y=x+2\displaystyle y = x + 2 into the corrected second equation:\n5x6(x+2)=85x - 6(x + 2) = -8\n5x6x12=85x - 6x - 12 = -8\nx=4impliesx=2-x = 4 \\implies x = 2\n\nSubstituting x=2\displaystyle x = 2 back into the first equation:\ny=2+2=3y = 2 + 2 = 3\n\nThus, the arithmetic means are barx=2\displaystyle \\bar{x} = 2 and bary=3\displaystyle \\bar{y} = 3, which is (2,3)\displaystyle (2, 3).\n\nHence, **Option B** is the correct answer.

About This Chapter: Correlation and Regression

Paper

Paper 3: Quantitative Aptitude

Weightage

4-6 Marks

Key Topics

Correlation Coefficient, Regression Equations

This chapter covers Correlation Coefficient, Regression 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.

Key Concepts to Understand

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