A biologist recorded the number of sea stars in each tide pool in a survey. The results are summarized in the table.
| Number of sea stars in a tide pool | Number of tide pools |
|---|---|
| 3 | k |
| 5 | 3 |
| 7 | 6 |
The mean number of sea stars per tide pool was 5. What was the median number of sea stars per tide pool?