Analysis and Approaches for IBDP Maths Ebook 1 | Page 305

Front Page
99
Paper 2 Section A – Regression of on
Example
The following table below shows the marks scored by six students on two different
assessments.
Assessment 1 ( x ) 21 25 28 31 36 34
Assessment 2 ( y ) 17 23 23 30 31 37
Let L
1
be the regression line of x on y . The equation of the line L
1
can be written in the
form x �ay � b .
(a) Find the values of a and b .
Let L
2
be the regression line of y on x . The lines L
1
and L
2
pass through the same
point with coordinates ( mn. , )
(b) Find the values of m and n .
[2]
[3]
Solution
(a) a � 0.7170668397
a � 0.717
A1 N1
b � 9.925373134
b � 9.93
A1 N1
(b) m � 29.16666667
(M1) for valid approach
m � 29.2
A1 N2
n � 26.83333333
n � 26.8
A1 N1
[2]
[3]
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