Question

There are 10 lamps in a hall. Each one of them can be switched on independently. The number of ways in which the hall can be illuminated is

• A. $10^{2}$
• B. 1023
• C. $2^{10}$
• D. 10 !

Answer 1

Answer: (B)

1023

Answer 2

Number of ways are = $2^{10} - 1 = 1023$

[– 1 corresponds to none of the lamps is being switched on.]