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_name_47 ( wins INTEGER, class VARCHAR, rank VARCHAR )

### Question ###
Tell me the average wins for class of 50cc and rank of 8th

### Accurate SQL ###

SELECT AVG(wins) FROM table_name_47 WHERE class = "50cc" AND rank = "8th"