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प्रश्न
There are 10 lamps in a hall. Each one of them can be switched on independently. Find the number of ways in which the hall can be illuminated ?
उत्तर
Total number of lamps = 10
A lamp can be either switched on or switched off.
Since, at least one lamp is to be kept switched on,
∴ The total number of ways are `2^10-1=1023`
Thus, the number of ways in which the hall can be illuminated are 1023.
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