We have n switches, each with probability pᵢ of being on and 1 - pᵢ of being off. What is the probability of c or more switches being on?
a) Σ[k=c to n] (n choose k) * pᵢᵏ * (1 - pᵢ)ⁿ⁻ᵏ
b) Σ[k=0 to c] (n choose k) * pᵢᵏ * (1 - pᵢ)ⁿ⁻ᵏ
c) Σ[k=c to n] (n choose k) * pᵢⁿ⁻ᵏ * (1 - pᵢ)ᵏ
d) Σ[k=0 to c] (n choose k) * pᵢⁿ⁻ᵏ * (1 - pᵢ)ᵏ
