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_27922491_20 (bbi VARCHAR, average VARCHAR)

### Question ###
What was the BBI for the bowler whose average is 24.50?

### Accurate SQL ###

SELECT bbi FROM table_27922491_20 WHERE average = "24.50"