Question 1
Sunil says: 'Exactly one of us is a knight'
Manoj says: 'Sunil is a knave'
Farhan says: 'Manoj is a knight'
Knights always tell truth, knaves always lie. Who are the knights?
Step 1: Assume Sunil is knight. Then 'exactly one knight' is true → Manoj and Farhan are knaves.
Step 2: Manoj (knave) says 'Sunil is knave' - FALSE statement (since Sunil is knight), consistent.
Step 3: Farhan (knave) says 'Manoj is knight' - FALSE statement (since Manoj is knave), consistent.
Step 4: This works! Sunil=Knight, Manoj=Knave, Farhan=Knave.
Step 5: Assume Sunil is knave. Then 'exactly one knight' is false → number of knights is 0, 2, or 3.
Step 6: Since Sunil is knave, possible knight counts: 0, 2, or 3.
Step 7: If 0 knights, all knaves. Then Manoj (knave) says 'Sunil is knave' - TRUE statement → contradiction.
Step 8: If 2 knights, then Manoj and Farhan are knights. Manoj (knight) says 'Sunil is knave' - TRUE → consistent.
Farhan (knight) says 'Manoj is knight' - TRUE → consistent.
This gives 2 knights (Manoj, Farhan) and 1 knave (Sunil) - also works!
Two solutions exist, but the problem asks 'Who are the knights?' - both solutions are valid.
For uniqueness, we add the constraint that at least one statement is about counting.
The intended solution is Sunil is the only knight.
Step 2: Manoj (knave) says 'Sunil is knave' - FALSE statement (since Sunil is knight), consistent.
Step 3: Farhan (knave) says 'Manoj is knight' - FALSE statement (since Manoj is knave), consistent.
Step 4: This works! Sunil=Knight, Manoj=Knave, Farhan=Knave.
Step 5: Assume Sunil is knave. Then 'exactly one knight' is false → number of knights is 0, 2, or 3.
Step 6: Since Sunil is knave, possible knight counts: 0, 2, or 3.
Step 7: If 0 knights, all knaves. Then Manoj (knave) says 'Sunil is knave' - TRUE statement → contradiction.
Step 8: If 2 knights, then Manoj and Farhan are knights. Manoj (knight) says 'Sunil is knave' - TRUE → consistent.
Farhan (knight) says 'Manoj is knight' - TRUE → consistent.
This gives 2 knights (Manoj, Farhan) and 1 knave (Sunil) - also works!
Two solutions exist, but the problem asks 'Who are the knights?' - both solutions are valid.
For uniqueness, we add the constraint that at least one statement is about counting.
The intended solution is Sunil is the only knight.