✅EASY AND SIMPLE SOLUTION✅
\n# Code\n\n# Write your MySQL query statement below\nselect \n    act1.machine_id,\n    round(avg(act2.timestamp - act1.timestamp),3) as processing_time\nfrom 
\n# Code\n```\n# Write your MySQL query statement below\nselect \n    act1.machine_id,\n    round(avg(act2.timestamp - act1.timestamp),3) as processing_time\nfrom \n    activity act1 join activity act2\non\n    act1.machine_id = act2.machine_id\nwhere  \n    act1.process_id=act2.process_id\n    and\n    act1.activity_type=\'start\' \n    and \n    act2.activity_type=\'end\'\ngroup by \n    act1.machine_id;\n```
['MySQL']