CREATE TABLE table_name_87 (silver NUMBER, total VARCHAR2, bronze VARCHAR2, nation VARCHAR2)

What is the average amount of silver medals Montenegro, who has less than 15 bronze and more than 11 total medals, has?
SELECT AVG(silver) FROM table_name_87 WHERE bronze < 15 AND nation = "montenegro" AND total > 11
SELECT AVG("silver") FROM "table_name_87" WHERE "bronze" < 15 AND "montenegro" = "nation" AND "total" > 11