Write SQL query to solve given problem: How many orders purchased by Aaron Bergman have been delivered with the slowest shipping speed?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(*) FROM people AS T1 INNER JOIN central_superstore AS T2 ON T1.`Customer ID` = T2.`Customer ID` WHERE T1.`Customer Name` = 'Aaron Bergman' AND T2.`Ship Mode` = 'Standard Class'