tell me the chip model produced by the company named "Nokia Corporation".
select chip_model from phone where company_name = "Nokia Corporation"
Okay, tell me the ROM size of those chip models.
select t1.rom_mib from chip_model as t1 join phone as t2 on t1.model_name = t2.chip_model where t2.company_name = "Nokia Corporation";
So, what is the average ROM size?
select avg(t1.rom_mib) from chip_model as t1 join phone as t2 on t1.model_name = t2.chip_model where t2.company_name = "Nokia Corporation"