Question 1
Ravi says: 'Farhan is a liar'
Farhan says: 'Gaurav is a truth-teller'
Gaurav says: 'Sunil and I are different types'
Sunil says: 'Ravi is a truth-teller'
If Ravi is a truth-teller, who must be a liar?
Given: If Ravi is a truth-teller
Step 1: Ravi tells truth → 'Farhan is liar' is true → Farhan is liar.
Step 2: Farhan (liar) says 'Gaurav is truth-teller' → this statement is false → Gaurav is liar.
Step 3: Gaurav (liar) says 'Sunil and I are different types' → this statement is false → Sunil is SAME type as Gaurav → Sunil is liar.
Step 4: Sunil (liar) says 'Ravi is truth-teller' → this statement is false → Ravi is liar → CONTRADICTION with our assumption!
This shows that Ravi CANNOT be a truth-teller under these statements.
However, the conditional question asks: IF we assume Ravi is truth-teller, who MUST be a liar? From step 1, Farhan must be a liar.
Therefore, under the given condition, Farhan must be a liar.
Step 1: Ravi tells truth → 'Farhan is liar' is true → Farhan is liar.
Step 2: Farhan (liar) says 'Gaurav is truth-teller' → this statement is false → Gaurav is liar.
Step 3: Gaurav (liar) says 'Sunil and I are different types' → this statement is false → Sunil is SAME type as Gaurav → Sunil is liar.
Step 4: Sunil (liar) says 'Ravi is truth-teller' → this statement is false → Ravi is liar → CONTRADICTION with our assumption!
This shows that Ravi CANNOT be a truth-teller under these statements.
However, the conditional question asks: IF we assume Ravi is truth-teller, who MUST be a liar? From step 1, Farhan must be a liar.
Therefore, under the given condition, Farhan must be a liar.