There are five rooms in my house — a hall, kitchen, study room, bedroom and dining room. There is one light in each room. Whenever the kitchen light is on, the study room light is off. Whenever the dining room light is on, the kitchen light is also on. Whenever the study room light is on, the hall light has to be on. How many lights, at the most, can be on simultaneously ?
This questions was previously asked in
PCS Previous year General Studies paper 2020 (CSAT)
Explanation:
- Kitchen and Study Room Condition: If the kitchen light is on, the study room light must be off.
- Dining and Kitchen Condition: If the dining room light is on, the kitchen light must be on as well.
- Study and Hall Condition: If the study room light is on, the hall light must also be on.
Maximizing Lights:
- Turn on the Bedroom, Dining Room, and Kitchen lights.
- According to the Dining and Kitchen condition, with the dining room light on, the kitchen light must also be on.
- According to the Kitchen and Study Room condition, if the kitchen light is on, the study room light must be off.
- You can also turn on the Hall light independently.
- Correct Option: 4 lights can be on simultaneously (Bedroom, Dining, Kitchen, Hall).
So, the correct answer is: Option 2: 4
.
![]()
By: Parvesh Mehta