2021 May TZ1 P2 Q2

The following table shows the data collected from an experiment.

The data is also represented on the following scatter diagram.

The relationship between \(x\) and \(y\) can be modelled by the regression line of \(y\) on \(x\) with equation \(y = ax + b\), where \(a, b \in \mathbb{R}\).

1. Write down the value of \(a\) and the value of \(b\).

   [2]

2. Use this model to predict the value of \(y\) when \(x = 18\).

   [2]

3. Write down the value of \(\bar{x}\) and the value of \(\bar{y}\).

   [1]

4. Draw the line of best fit on the scatter diagram.

   [2]