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Question
Answer the following:
A hall has 12 lamps and every lamp can be switched on independently. Find the number of ways of illuminating the hall.
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Solution
There are 12 lamps, i.e., n = 12.
Now, if at least one of the switches is 'on' the hall can be illuminated.
∴ the number of ways in which the hall can be illuminated = 2n – 1
= 212 – 1
= 4096 – 1
= 4095
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