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_27 (laps INTEGER, time_retired VARCHAR, grid VARCHAR)

### Question ###
What was the average amount of laps for competitors with a grid that was more than 11 and a Time/Retired of +28.108?

### Accurate SQL ###

SELECT AVG(laps) FROM table_name_27 WHERE time_retired = "+28.108" AND grid > 11