Question 1
Manoj says: 'Exactly one of us is a knight'
Deepa says: 'Manoj is a knave'
Meera says: 'Deepa is a knight'
Knights always tell truth, knaves always lie. Who are the knights?
Step 1: Assume Manoj is knight. Then 'exactly one knight' is true → Deepa and Meera are knaves.
Step 2: Deepa (knave) says 'Manoj is knave' - FALSE statement (since Manoj is knight), consistent.
Step 3: Meera (knave) says 'Deepa is knight' - FALSE statement (since Deepa is knave), consistent.
Step 4: This works! Manoj=Knight, Deepa=Knave, Meera=Knave.
Step 5: Assume Manoj is knave. Then 'exactly one knight' is false → number of knights is 0, 2, or 3.
Step 6: Since Manoj is knave, possible knight counts: 0, 2, or 3.
Step 7: If 0 knights, all knaves. Then Deepa (knave) says 'Manoj is knave' - TRUE statement → contradiction.
Step 8: If 2 knights, then Deepa and Meera are knights. Deepa (knight) says 'Manoj is knave' - TRUE → consistent.
Meera (knight) says 'Deepa is knight' - TRUE → consistent.
This gives 2 knights (Deepa, Meera) and 1 knave (Manoj) - 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 Manoj is the only knight.
Step 2: Deepa (knave) says 'Manoj is knave' - FALSE statement (since Manoj is knight), consistent.
Step 3: Meera (knave) says 'Deepa is knight' - FALSE statement (since Deepa is knave), consistent.
Step 4: This works! Manoj=Knight, Deepa=Knave, Meera=Knave.
Step 5: Assume Manoj is knave. Then 'exactly one knight' is false → number of knights is 0, 2, or 3.
Step 6: Since Manoj is knave, possible knight counts: 0, 2, or 3.
Step 7: If 0 knights, all knaves. Then Deepa (knave) says 'Manoj is knave' - TRUE statement → contradiction.
Step 8: If 2 knights, then Deepa and Meera are knights. Deepa (knight) says 'Manoj is knave' - TRUE → consistent.
Meera (knight) says 'Deepa is knight' - TRUE → consistent.
This gives 2 knights (Deepa, Meera) and 1 knave (Manoj) - 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 Manoj is the only knight.