Question 13
A room has three light bulbs, X, Y and Z, and four switches:
- Switch 1 turns Y on and X off.
- Switch 2 turns X and Y on and Z off.
- Switch 3 turns Z on and Y off.
- Switch 4 turns X on.
All the bulbs are initially off. A beaver wants all three bulbs to be on. Which sequence of switches below achieves this fastest?
If a bulb is already on (or off), pressing a switch to turn it on (or off) does not change its state.
- Switch 1 turns Y on and X off.
- Switch 2 turns X and Y on and Z off.
- Switch 3 turns Z on and Y off.
- Switch 4 turns X on.
All the bulbs are initially off. A beaver wants all three bulbs to be on. Which sequence of switches below achieves this fastest?
If a bulb is already on (or off), pressing a switch to turn it on (or off) does not change its state.