Higher November 2019 Paper 3 Q4
4 The table gives information about the times taken, in seconds, by 18 students to run a race.
| Time (\(t\) seconds) | Frequency |
|---|---|
| \(5 \lt t \leqslant 10\) | 1 |
| \(10 \lt t \leqslant 15\) | 2 |
| \(15 \lt t \leqslant 20\) | 7 |
| \(20 \lt t \leqslant 25\) | 8 |
Work out an estimate for the mean time.
Give your answer correct to 3 significant figures. (3)
| Answer | Mark | Mark scheme |
|---|---|---|
| 18.6 | M1 | for finding 4 products within intervals (including end points) |
| M1 | for \(\Sigma \text{``}fx\text{''} \div (1 + 2 + 7 + 8)\) or \((7.5 \times 1 + 12.5 \times 2 + 17.5 \times 7 + 22.5 \times 8) \div (1 + 2 + 7 + 8)\) or \((\text{``}7.5\text{''} + \text{``}25\text{''} + \text{``}122.5\text{''} + \text{``}180\text{''}) \div \text{``}18\text{''}\) or \(\text{``}335\text{''} \div \text{``}18\text{''}\) | |
| A1 | for 18.6(111…) |
Additional guidance
| Min \(fx\) | Max \(fx\) |
|---|---|
| 5 | 10 |
| 20 | 30 |
| 105 | 140 |
| 160 | 200 |
\(\Sigma \text{``}fx\text{''}\) must come from 4 products \(fx\) within intervals (including end points)