Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_11414 ( "Name" text, "Builder" text, "Type" text, "Date" real, "Works number" real )

### Question ###
What is the average work number of Snowdon Ranger with the builder Vulcan Foundry?

### Accurate SQL ###

SELECT AVG("Works number") FROM table_11414 WHERE "Builder" = 'vulcan foundry' AND "Name" = 'snowdon ranger'