Question 1
Rohan says: 'The number of liars among us is exactly one'
Sunil says: 'Rohan and Deepa are the same type'
Deepa says: 'At least one of us is a truth-teller'
If the initial correct deduction shows Rohan is a Truth-teller, but we hypothetically assume Rohan was a Liar, how many Truth-tellers would there be?
First, solve the original puzzle:
- If Rohan is truth-teller -> exactly one liar -> p2 and p3 are truth-tellers.
Then p2 (truth) says 'Rohan and Deepa same type' - true (both truth) - consistent.
p3 (truth) says 'at least one truth-teller' - true - consistent.
Solution: Rohan=T, Sunil=T, Deepa=L
Now, hypothetically assume Rohan is liar instead of truth-teller.
Then we need to re-solve:
- Rohan liar -> statement 1 false -> number of liars is NOT exactly one -> 0, 2, or 3 liars.
- If 0 liars, all truth-tellers. Then Rohan truth - contradicts Rohan liar.
- If 2 liars, then Sunil and Deepa are liars. Then Sunil liar says 'Rohan and Deepa same type' - Rohan liar, Deepa liar -> same type -> true statement, but liar can't make true - contradiction.
- If 3 liars, all are liars. Then Sunil liar says 'Rohan and Deepa same type' - both liars -> same -> true statement - contradiction.
- Therefore, no consistent assignment exists when Rohan is liar.
Thus, if we hypothetically assume Rohan is liar, there would be ZERO truth-tellers.
- If Rohan is truth-teller -> exactly one liar -> p2 and p3 are truth-tellers.
Then p2 (truth) says 'Rohan and Deepa same type' - true (both truth) - consistent.
p3 (truth) says 'at least one truth-teller' - true - consistent.
Solution: Rohan=T, Sunil=T, Deepa=L
Now, hypothetically assume Rohan is liar instead of truth-teller.
Then we need to re-solve:
- Rohan liar -> statement 1 false -> number of liars is NOT exactly one -> 0, 2, or 3 liars.
- If 0 liars, all truth-tellers. Then Rohan truth - contradicts Rohan liar.
- If 2 liars, then Sunil and Deepa are liars. Then Sunil liar says 'Rohan and Deepa same type' - Rohan liar, Deepa liar -> same type -> true statement, but liar can't make true - contradiction.
- If 3 liars, all are liars. Then Sunil liar says 'Rohan and Deepa same type' - both liars -> same -> true statement - contradiction.
- Therefore, no consistent assignment exists when Rohan is liar.
Thus, if we hypothetically assume Rohan is liar, there would be ZERO truth-tellers.