You are an accounts analyst for an electrical billing company. According to industry statistics, for the three hottest months of summer, homeowners spend on average $441.84 for total electrical utility cost (standard deviation of $90). How much does a household have to spend to be in the top 20% of electrical users? a) $517.44 or more Ob) $517.44 or less c) between $531.84 and $621.84 O d) $531.84 or more