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Since each light can be switched on independently,
there are two options for each bulb (on or off)
∴Total no. of ways the bulbs can be operated= 210
This includes all the bulbs are kept in off so that the room is not illuminated.
∴ The no. of ways in which the room is illuminated=210−1=1023
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total no:of ways are 210 (for ON &OFF)
no:of ways room illuminated is 1 way switch off all lights
so no:of ways room glow is 210-1=1023
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