Paper 4: Fundamentals of Business Mathematics & Statistic

FUNDAMENTALS OF BUSINESS MATHEMATICS AND STATISTICS I 6.29

∑(X - 20)(Y-10) = ∑xy = 40
Regression Equation of X and Y

X - X = bXY(Y-Y)

Where XY 2
b XY^40 0.667
= Y = 60 =

X - 20 = 0.667(Y-10)

X - 20 = 0.667Y - 6.67

X = 20 + 0.667Y - 6.67

X = 0.667Y + 13.33

Regression Equation of Y and X

Y - Y = bYX(X-X)

Where YX 2
b XY^40 0.4
= X = 100 =

Y - 10 = 0.4 (X - 20)

Y - 10 = 0.4 X -8

Y = 10 + 0.4X - 8

Y = 0.4X + 2

r b b= XY YX

= 0.4x0.667

= 0.2668

= 0.517

Example19 :

Following are the marks in Maths and English
Maths English
Mean 40 50
Standard Deviation 10 16
Coefficient of correlation 0.5
(1) Find two regression equation
(2) Find the most likely marks in Maths if marks in English are 40.