In a survey conducted in a town, the number of children in the houses is given below:
| Families | Number of children |
| More than or equal to 300 | 10 |
| More than or equal to 600 | 10 |
| More than or equal to 900 | 6 |
| More than or equal to 1200 | 3 |
| More than or equal to 1500 | 1 |
1. The lower limit of the median class is .
2. The upper limit of the median class is .
3. The median is .
4. The construction of cumulative distribution table is useful in determining the .
5. Which family group have the maximum number of children?