NIMCET 2013 Logical Reasoning Question 74 with Solution

Question 74

Logical Reasoning Puzzles Hard

Direction: Questions are based on the following: There are three switches A, B and C which can be in ON/OFF position. Their settings change as per the following rules: i) If A is the only switch as ON, change B to ON. ii) If A and B are only switches as ON, change C to ON. iii) If all three switches are ON, change C to OFF. iv) For all other situations, all switches in ON are changed to OFF and all switches in OFF are changed to ON If switches A and B are ON and C is OFF, their changed settings will be:

(A) A ON, B OFF, C OFF

(B) A ON, B ON, C ON

(C) A ON, B OFF, C ON

(D) A OFF, B ON, C OFF

View Dynamic Solution & Explanation ▼

Correct Solution: Option B

Step-by-step Solution:

Quick Solution

This is a rule-based logic puzzle. The key is to identify the starting configuration of the switches and then find which of the four specific rules applies to that exact situation before determining the outcome.

1. Identify the Initial State and Find the Correct Rule

The problem asks for the outcome when the initial state is: A is ON, B is ON, and C is OFF.

Now, we check the list of rules to see which one matches this specific state:

Rule: "If A is the only switch as ON..."
This condition (A ON, B OFF, C OFF) does not match our initial state.
Rule: "If A and B are only switches as ON..."
This condition (A ON, B ON, C OFF) is an exact match for our initial state. This is the rule we must follow.
Rule: "If all three switches are ON..."
This condition (A ON, B ON, C ON) does not match our initial state.
Rule: "For all other situations..."
This rule does not apply, because our situation is explicitly covered by Rule (ii).

2. Apply the Rule to Find the Final State

- Since our initial state matches the condition in Rule (ii), we must follow its instruction.
- The instruction for Rule (ii) is: "change C to ON".

- We start with {A ON, B ON, C OFF}.
- The switches A and B are not affected. Switch C is changed from OFF to ON.

Final Answer: The changed settings will be A ON, B ON, C ON.