Answer:
So for his mark will be in between 82 to 130 for C grade
Step-by-step explanation:
We have given that for C grade the minimum average mark should be 77 and maximum average mark should be 85
There are 6 subjects
So total minimum mark = 6×77 =462
And total maximum mark = 85×6 =510
He has five grades as 74,78,76,67,85
So sum of five grades = 74+78+76+67+85=380
Let he get x marks in 6th
So for minimum mark in 6th grade x+380 = 462
x = 462-380=82
For maximum mark x+380=510
x = 510-380 =130
So for his mark will be in between 82 to 130 for C grade