Question

Six students A,B,C,D,E,F study in 6 different classes in a school. The classes are from class 5, class 6, class 7, class 8, class 9, class 10. The order of students and their classes is random.it is also known that:
1) E studies in neither class $7$ nor class $10$.
2) B and D in classes $5$ and $9$, but not necessary in that order.
3) The product of the classes of E and A is either $56$ or $60$.
4) C is not the oldest amongst the students and hence it is known that he does not study in class $10.$
5) If it is known that E studies in class $6$, then in which class does C study?

• A. Class 7
• B. Class 8
• C. Class 10
• D. Either A or B

Answer 1

The correct option is D Either A or B

Given,
1) E studies in neither in class $7$ nor $10$.
2) B and D are in class $5$ and $9$.
3) The product of the classes of E and A is either $56$ or $60$.
4) C not study in class 10
It is given that E studies in class in 6.
From 3,
Product of class of E and A = either $56$ or $60$
$E\times A=56\times 60$
$6\times A=56\times 60$

A must be in class $10$ because no other product satisfy the equation i.e. $6\times 8=48,6\times 9=54$
So, $E=6,A=10$
B and D are in $5$ and $9$,
So, F and C must be either 7 and 8. Thus, C either in 7 or 8.