On one block of “Eat Street” in downtown Minneapolis there are 10 restaurants to choose from. The waiting time for each restaurant is exponentially distributed with respective parameters λ₁, . . . , λ₁₀. Bob will decide to eat at restaurant i with probability p_i for i = 1, . . . , 10 (p₁ + · · · + p₁₀ = 1). What is Bob’s expected waiting time?