In general, the IGNOU calculates the percentage on a 30:70 basis.
Assignments = 30
Theory Exam = 70
Initially, assignments and theory will be graded out of 100. Then it will be converted based on the ratio. So, 30% of the total assignment marks and 70% of the theory exam, both marks are totaled into one.
The percentage is calculated by dividing total marks by the number of subjects, which is 309.7/5= 61.94.
So that's how the marks or percentage or grade calculation works.