Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Romanised name | Chinese name | age at appointment | Foreign nationality | Portfolio attachment | Govt salary |
| --- | --- | --- | --- | --- | --- |
| Chan Chi-yuen, Paul | 陳智遠 | 28.0 | N/A | Food and Health | HK$ 134,150 |
| Cheung, Raymond Man-to | 張文韜 | 46.0 | N/A | Education | HK$134,150 |
| Choy Siu-min, Linda | 蔡少綿 | 37.0 | N/A | Environment | HK$149,055 |
| Lo Yik-kee, Victor | 盧奕基 | 55.0 | British | Security | HK$134,150 |
| Mok Yee-tuen, Zandra | 莫宜端 | 35.0 | N/A | Labour and Welfare | HK$134,150 |
| Ng Kit-shuen, Katherine | 伍潔鏇 | 34.0 | an Singapore | Financial Services and the Treasury | HK$163,960 |
| Tsui Ying-wai, Caspar | 徐英偉 | 31.0 | Canadian | Home Affairs | HK$134,150 |
| Yip Kan-chuen, Frankie | 葉根銓 | 38.0 | N/A | Financial Secretary | HK$134,150 |
| Young Chit-on, Jeremy | 楊哲安 | 32.0 | British | Food & Health | HK$134,150 |
Question:
What is the average age at appointment of those attached to security?
Answer:
55.0