Gate 2008 IT DBMS Relational Please help with this question . Stud...
Gate 2008 IT DBMS Relational
Please help with this question .

Student (school-id, sch-roll-no, sname, saddress)
School (school-id, sch-name, sch-address, sch-phone)
Enrolment(school-id sch-roll-no, erollno, examname)
ExamResult(erollno, examname, marks)

Consider the following tuple relational calculus query.
{t | ∃ E ∈
Enrolment t = E.school-id ∧
| {x | x ∈ Enrolment ^ x.school-id = t ∧

(∃ B ∊ ExamResult B.erollno = x.erollno ∧
B.examname = x.examname ∧

B.marks > 35)}| /

| {x | x ∊ Enrolment ∧

x.school-id = t}| * 100 > 35}
If a student needs to score more than 35 marks to pass an exam, what does the query return?

a The empty set
b schools with more than 35% of its students enrolled in some exam or the other
c schools with a pass percentage above 35% over all exams taken together
d schools with a pass percentage above 35% over each exam

2Comments
Apoorva Jain @apoorvaj1 17 Dec 2018 12:39 pm
@ranita mam plz help
Pritam Prasun @pritam 23 Dec 2018 03:58 pm
Apoorva, Please correct the question. It seems to have many typos.

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