Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the average area for code 98030 with population over 312?

### Inputs:
table_name: table, columns: ['Code', 'Type', 'Name', 'Area (km 2 )', 'Population', 'Regional County Municipality', 'Region']

### Response:
SELECT AVG Area (km 2 ) FROM table WHERE Code = 98030 AND Population > 312