| Load \(x\) | \(0 \leqslant x \leqslant \frac { 1 } { 4 }\) | \(\frac { 1 } { 4 } < x \leqslant \frac { 1 } { 2 }\) | \(\frac { 1 } { 2 } < x \leqslant \frac { 3 } { 4 }\) | \(\frac { 3 } { 4 } < x \leqslant 1\) |
| Frequency | 126 | 209 | 131 | 46 |
| Factory | A | B | C | D | E | F | G | H | I |
| Number before installation | 8 | 12 | 6 | 4 | 14 | 22 | 4 | 13 | 14 |
| Number after installation | 6 | 11 | 0 | 1 | 18 | 10 | 11 | 5 | 4 |
| Factory | T | U | V | W | X | Y | Z |
| Cost before installation | 1215 | 95 | 546 | 467 | 2356 | 236 | 550 |
| Cost after installation | 1268 | 110 | 578 | 480 | 2417 | 318 | 620 |
| Vehicle type | Mean | Standard deviation |
| Cars | 60.2 | 5.2 |
| Coaches | 33.9 | 6.3 |
| Lorries | 52.4 | 4.9 |
| Shop | A | B | C | D | E | F | G | H | I | J | K |
| \% days lost before | 3.5 | 5.0 | 3.5 | 3.2 | 4.5 | 4.9 | 4.1 | 6.0 | 6.8 | 8.1 | 6.0 |
| \% days lost after | 1.8 | 4.3 | 2.9 | 4.5 | 4.4 | 5.8 | 3.5 | 6.7 | 6.4 | 5.4 | 5.1 |
| Length \(x\) (hundreds of metres) | Observed frequency | Probability |
| \(0 < x \leqslant 0.5\) | 21 | 0.2653 |
| \(0.5 < x \leqslant 1\) | 24 | 0.1722 |
| \(1 < x \leqslant 2\) | 12 | 0.2025 |
| \(2 < x \leqslant 3\) | 15 | 0.1100 |
| \(3 < x \leqslant 5\) | 13 | 0.1094 |
| \(5 < x \leqslant 10\) | 9 | 0.0874 |
| \(x > 10\) | 6 | 0.0532 |
| Smokers | 77 | 85 | 90 | 98 | |
| Non-smokers | 59 | 64 | 68 | 80 | 88 |
| \(X\) | |||
| \cline { 2 - 5 } \multicolumn{1}{l}{} | - 1 | 0 | 1 |
| 1 | 0.24 | 0.22 | 0.04 |
| 2 | 0.26 | 0.18 | 0.06 |