Hello Shubhangi Agarwal,
I have created a sample workbook showing how to accomplish an avg of the top 5 results per day of the totalMemoryUsed_max value. You did not specify a version so this is in Tableau 10.1.
If you have any questions, please let me know. Others might be able to achieve this with a LOD calcualation a bit easier but this works.
Can u pls share sample solution workbook.?