Percentage increase in marks in various periodical exams compared to the previous exams are:

For Jun 01 =		(365 - 360)	x 100		% = 1.39%.
		360

For Aug 01 =		(370 - 365)	x 100		% = 1.37%.
		365

For Oct 01 =		(385 - 370)	x 100		% = 4.05%.
		370

For Dec 01 =		(400 - 385)	x 100		% = 3.90%.
		385

For Feb 02 =		(404 - 400)	x 100		% = 1.25%.
		400

Clearly, highest percentage increase in marks is in Oct 01.

Here it is clear from the graph that the student obtained 360, 365, 370, 385, 400 and 405 marks in periodical exams held in Apr 01, Jun 01, Aug 01, Oct 01, Dec 01 and Feb 02 respectively.

Required percentage =		405	x 100		% = 112.5%.
		360

Average marks obtained in all the periodical exams

=	1	x [360 + 365 + 370 + 385 + 400 + 405] = 380.83 381.
	6

As is clear from the graph, the total marks obtained in periodical exams, go on increasing. Since, the maximum marks for all the periodical exams are the same; it implies that the percentage of marks also goes on increasing.

Thus, in none of the periodical exams, there is a fall in percentage of marks compared to the previous exam.