## Exam Style Question on Correlation## A mathematics exam-style question with a worked solution that can be revealed gradually |

Question id: 369. This question is similar to one that appeared in an IB AA Standard paper (specimen) for 2021. The use of a calculator is allowed.

A pair of twins, Percy and Patsy, take Maths assessment tests each week. Their teacher records their scores in this table:

Week 1 | Week 2 | Week 3 | Week 4 | Week 5 | Week 6 | Week 7 | Week 8 | |
---|---|---|---|---|---|---|---|---|

Percy (\(x\)) | 52 | 60 | 58 | 61 | 65 | 60 | 70 | 72 |

Patsy (\(y\)) | 50 | 60 | 61 | 59 | 64 | 64 | 68 | 73 |

(a) Find an equation of the regression line of \(x\) on \(y\). The equation should be written in the form \(x = ay + b\).

(b) Find an equation of the regression line of \(y\) on \(x\). The equation should be written in the form \(y = ax + b\)

(c) Find the coordinates of the point of intersection of these two lines.

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