given
The police arrested four criminals – P, Q, R and S. The criminals knew each other. They made the following statements:
P says “Q committed the crime.”
Q says “S committed the crime.”
R says “I did not do it.”
S says “What Q said about me is false.”
Assume only one of the arrested four committed the crime and only one of the statements made above is true. Who committed the crime?
Case I:
S and R are criminal in the result is impossible because only one person committed the crime.
Case II:
Q and R are criminal in the result is impossible because only one person committed the crime.
Case III:
SNC and SC in the result which is contradiction. [S committed crime and same time not committed crime which is contradiction]
Case IV:
R is criminal in the result.
Hence this case satisfies only one person committed the crime.
Total number of students = 60 + 80 + 30 + 38 + 5 + 10 + 2 = 225
25% = 225