The table below shows the number of girls who ran certain distance.

-------------|---|----|---|----|----|--Distance(Km) | 5 | 10 |15 | 20 | 25 |
-------------|---|----|---|----|----|--No. of girls | 2 | 1 | 3 | 4 | X |
-------------|---|----|---|----|----|-- Given that the median is 20Km, find the largest possible value of X

There are 10 girls who went 20 km or less. If 20 is the median, there can be no more than 6 who went 20 km or more (for a total of 10).