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:
| Year | Competition | Venue | Position | Notes |
| --- | --- | --- | --- | --- |
| 1994 | Commonwealth Games | Victoria, Canada | 6th | 400 m h |
| 1995 | World Championships | Gothenburg, Sweden | 6th | 400 m h |
| 1997 | World Championships | Athens, Greece | 7th | 4x400 m relay |
| 1998 | Commonwealth Games | Kuala Lumpur, Malaysia | 3rd | 400 m h |
| 1998 | African Championships | Dakar, Senegal | 2nd | 400 m h |
| 1999 | All-Africa Games | Johannesburg, South Africa | 2nd | 400 m h |
Question:
how long was the relay at the 1997 world championships that ken harden ran
Answer:
4x400 m relay