1MA0 Higher June 2012 Paper 2 Q13
13 Bob asked each of 40 friends how many minutes they took to get to work.
The table shows some information about his results.
| Time taken (\(m\) minutes) | Frequency |
|---|---|
| \(0 \lt m \leqslant 10\) | 3 |
| \(10 \lt m \leqslant 20\) | 8 |
| \(20 \lt m \leqslant 30\) | 11 |
| \(30 \lt m \leqslant 40\) | 9 |
| \(40 \lt m \leqslant 50\) | 9 |
Work out an estimate for the mean time taken. (4)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| 5×3+15×8+25×11+35×9+45×9 =1130 1130 ÷ 40 | 28.25 | 4 | M1 for finding \(fx\) with \(x\) consistent within intervals (including the end points) allow 1 error M1 (dep) for use of all correct mid-interval values M1 (dep on first M1) for \(\Sigma fx \div 40\) or \(\Sigma fx \div \Sigma f\) A1 for 28.25 or \(28\frac{1}{4}\) |