Question: While searching for a Mechanic, Pranjal met three locals - Harsh, Akash and Raju - who always gave two replies to any question. Among them one is a truth teller, one is a liar and one is an alternator. When Pranjal asked them, "Who among you is the Mechanic?", their replies were :
Harsh: I am the Mechanic. Akash is a liar
Who is the mechanic?
Explanation:
Assuming,
Case 1 : Harsh is the truth-teller i.e., both his statements are correct.
∴ Harsh is the mechanic, Akash is liar and Raju is alternator.
Checking for statements of Akash (liar): His both statements are false, which fits well with our assumption.
Checking for statements of Raju (alternator): His both statements are false, which contradicts our assumption.
∴ Harsh cannot be the truth-teller.
Case 2 : Akash is the truth-teller i.e., both his statements are correct.
∴ Akash is the mechanic, Raju is liar and Harsh is alternator.
Checking for statements of Raju (liar): His first statement is true which contradicts our assumption.
∴ Akash cannot be the truth-teller.
Case 3 : Raju is the truth-teller i.e., both his statements are correct.
∴ Akash is the mechanic, Harsh is liar and Akash is alternator.
Checking for statements of Harsh (liar): His both statement are false, which fits well with our assumption.
Checking for statements of Akash (alternator): His first statement is true and second statement is false, which fits well with our assumption
∴ Akash is the mechanic.
Hence, option (b).