Intermediate November 2020 Unit 2 Q14
14. Data for different values of \(t\) are shown in the table below.
| \(t\) | Frequency |
|---|---|
| \(0 \leqslant t < 5\) | 8 |
| \(5 \leqslant t < 10\) | 0 |
| \(10 \leqslant t < 15\) | 7 |
| \(15 \leqslant t < 20\) | 5 |
Calculate an estimate for the mean value of \(t\). [4]
| Scheme | Marks | Comments |
|---|---|---|
| (Mid-points) 2·5, (7·5), 12·5 and 17·5. | B1 | Allow for sight of mid-points. |
| 8 × 2·5 + (0 × 7·5) + 7 × 12·5 + 5 × 17·5 ( 20 + 0 + 87·5 + 87·5 = 195) | M1 | F.T. ‘their mid-points’ including bounds, provided they fall within the classes (including lower and upper bounds and used consistently). |
| ÷ 20 | m1 | |
| = 9.75 | A1 | C.A.O. |