Analysis and Approaches for IBDP Maths Ebook 1 | Page 300

Your Practice Set – Analysis and Approaches for IBDP Mathematics
3. The following table shows the Mathematics test scores ( x ) and the Physics test scores ( y )
of 7 students.
Mathematics test scores ( x ) 14 19 16 20 30 17 11
Physics test scores ( y ) 16 19 18 23 30 16 19
(a)
The relationship between the variables is modelled by the regression equation
y �ax � b .
(i) Write down the value of a and of b .
(ii) Hence, estimate the Physics test score of a student whose Mathematics test
score is 25.
[4]
A teacher believes that the relationship between the Mathematics test scores ( x ) and the
Chemistry test scores ( w ) of the students can be modelled by a linear regression equation.
(b)
The teacher describes the correlation as very strong and negative. Circle the
value below which best represents the correlation coefficient.
0.989 0.178 0 � 0.178
� 0.989
[1]
(c) The teacher’s model is w� �0.18x� 25.6 . Use his model to predict the difference
in Chemistry test scores of two students if the difference of their Mathematics test
scores is 3.
[2]
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