Suppose that 8 balls are put into 4 boxes, with each ball independently being put in box i with probability p_i , ⁴_i=1 p_i = 1. Find the expected number of boxes that have at most 1 ball. What is the expected number of boxes when a) p₁ = p₂ = p₃ = p₄ = 0.25 and b) p₁ = 1, p₂ = p₃ = p₄ = 0.