All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

(i)

Model A
Model A

Model B
Model B
Model C
Model C

(ii)

Scatter diagram
Scatter diagram

(iii)
Since the date points exhibit a curvilinear relationship with a negative gradient and concaving downwards, Model A is the most appropriate.

From the Graphing Calculator, r = -0.939

(iv)
From the Graphing Calculator, required regression line: y = 189.748 - 0.0046198 x^{2}
\therefore,~ \mathrm{Distance~travelled} = 134 \mathrm{km}

KS Comments:

The first part of this question tests students on their understanding of graphs. Students that have difficulties with this, should attempt to fit in simple values into graphing calculator.

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