$6\mathrm{.}2$ Consider a database that includes the entity sets student, course, and section

from the university schema and that additionally records the marks that students

receive in different exams of different sections.

a$.$ Construct an E$-$R diagram that models exams as entities and uses a ternary

relationship as part of the design

b$.$ Construct an alternative E$-$R diagram that uses only a binary relationship

between student and section. Make sure that only one relationship exists

between a particular student and section pair, yet you can represent the

marks that a student gets in different exams.