A student investigated the shell height of limpets on two different shores. Their results are shown in Table 1.
| Limpet | Shell height in millimetres (mm) | |
|---|---|---|
| Exposed shore | Sheltered shore | |
| 1 | 18 | 12 |
| 2 | 20 | 14 |
| 3 | 19 | 13 |
| 4 | 21 | (28) |
| 5 | 17 | 15 |
| Mean | 19 | 13.5 |
Why did the student not include the circled shell height of (28) when calculating the mean for the sheltered shore?
It has not been measured in millimetres.
It is the mode value.
It is an anomalous result.
It is a repeat measurement.
