Suppose the Amount of Heating Oil Used Annually by Households

Short Answer

Suppose the amount of heating oil used annually by households in Iowa is normally distributed with mean 200 gallons per household per year and standard deviation 40 gallons of heating oil per household per year.
What is the probability a randomly selected Iowa household uses more than 150 gallons of heating oil per year?
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What is the probability a randomly selected Iowa household uses between 180 and 300 gallons per year?
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If the members of a particular household were scared into using fuel conservation measures by newspaper accounts of the probable price of heating oil next year, and they decided they wanted to use less oil than 97.5% of all other Iowa households currently using heating oil, what is the maximum amount of oil they can use and still accomplish their conservation objective?
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