What is the average ROM size of phones produced by the company named "Nokia Corporation"?
CREATE TABLE phone (chip_model VARCHAR, Company_name VARCHAR); CREATE TABLE chip_model (ROM_MiB INTEGER, Model_name VARCHAR)
[SQL] 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" [/SQL]