In this question, a question is followed by two statements numbered (I) and (II). You have to decide whether the data provided in the statements are sufficient to answer the question. Read both the statements and decide the appropriate answer.
How many students of class 11th have got exactly 80% marks in Physics in annual examination, if total number of students in the class is 80?
I 45 students of class 11th have got more than 80% marks in Physics in annual examination.
II 30 students of class 11th have got less than 80% marks in Physics in annual examination.

45 students have got more than 80% marks.

So:

More than 80% = 45 students

Total = 80 students

We can’t find exactly 80% because we don’t know how many got less than 80%.
→ Missing information.

Hence, Statement I alone is NOT sufficient.

30 students have got less than 80% marks.

So:

Less than 80% = 30 students

Total = 80 students

We can’t find exactly 80% because we don’t know how many got more than 80%.
→ Missing information.

Hence, Statement II alone is NOT sufficient.

From I and II:

More than 80% = 45

Less than 80% = 30

Total = 80

Therefore,
Exactly 80% = 80 − (45 + 30) = 5 students