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

Question id: 53. This question is similar to one that appeared on an IB Standard paper in 2014. The use of a calculator is allowed.

The following table shows the average weights for given heights in a population of men.

Heights (x cm) | 160 | 165 | 170 | 175 | 180 | 185 |

Weights ( y kg) | 65.1 | 67.9 | 70.1 | 72.8 | 75.4 | 77.2 |

(a) The relationship between the variables is modelled by the regression equation \(y = ax + b\). Write down the value of \(a\) and of \(b\).

(b) Use this relationship to estimate the weight of a man whose height is 177 cm.

(c) Find the correlation coefficient.

(d) State which two of the following describe the correlation between the variables.

- strong
- zero
- positive
- negative
- no correlation
- weak

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