| Date | May 2014 | Marks available | 1 | Reference code | 14M.2.sl.TZ1.3 |
| Level | SL only | Paper | 2 | Time zone | TZ1 |
| Command term | Write down | Question number | 3 | Adapted from | N/A |
Question
The following table shows the average weights ( y kg) for given heights (x cm) in a population of men.
| Heights (x cm) | 165 | 170 | 175 | 180 | 185 |
| Weights (y kg) | 67.8 | 70.0 | 72.7 | 75.5 | 77.2 |
The relationship between the variables is modelled by the regression equation \(y = ax + b\).
Write down the value of \(a\) and of \(b\).
The relationship between the variables is modelled by the regression equation \(y = ax + b\).
Hence, estimate the weight of a man whose height is 172 cm.
Write down the correlation coefficient.
State which two of the following describe the correlation between the variables.
| strong | zero | positive |
| negative | no correlation | weak |
Markscheme
\(a = 0.486\) (exact) A1 N1
\(b = - 12.41\) (exact), \(-12.4\) A1 N1
[2 marks]
correct substitution (A1)
eg \(0.486(172) - 12.41\)
\(71.182\)
\(71.2\) (kg) A1 N2
[2 marks]
\(r = 0.997276\)
\(r = 0.997\) A1 N1
[1 mark]
strong, positive (must have both correct) A2 N2
[2 marks]
