Edexcel FS2 AS 2022 June — Question 3

Exam BoardEdexcel
ModuleFS2 AS (Further Statistics 2 AS)
Year2022
SessionJune
TopicLinear regression
TypeCalculate regression line then predict

  1. Gabriela is investigating a particular type of fish, called bream. She wants to create a model to predict the weight, \(w\) grams, of bream based on their length, \(x \mathrm {~cm}\).
For a sample of 27 bream, some summary statistics are given below. $$\begin{gathered} \bar { x } = 31.07 \quad \bar { w } = 628.59 \quad \sum w ^ { 2 } = 11386134
\mathrm {~S} _ { x w } = 13082.3 \quad \mathrm {~S} _ { x x } = 260.8 \end{gathered}$$
  1. Find the value of the product moment correlation coefficient between \(x\) and \(w\)
  2. Explain whether the answer to part (a) is consistent with a linear model for these data.
  3. Find the equation of the regression line of \(w\) on \(x\) in the form \(w = a + b x\) A residual plot for these data is shown below.
    \includegraphics[max width=\textwidth, alt={}, center]{128c408d-3e08-4f74-8f19-d33ecd5c882f-06_931_1790_1107_139} One of the bream in the sample has a length of 32 cm .
  4. Find its weight.
  5. With reference to the residual plot, comment on the model for bream with lengths above 33 cm .