The question is incomplete. The complete question is :
A bulb can either be on or off. A board contains 20 bulbs connected to a randomization circuit that lights up a random sequence every time it is turned on. What is the probability that all the lights will switch on ?
Solution :
It is given that :
There is board connected to = 20 bulbs
And one can either be put ON or put OFF.
Therefore the chance that a bulb is ON =
It is given that every time a bulb turns ON, the board lights up in a random sequence.
Therefore, the probability of all the lights to be switched ON is given by :