Energy Consumption—Dishwashers: The total amount of energy that the Kitchen Master dishwas...

Energy Consumption—Dishwashers: The total amount of energy that the Kitchen Master dishwasher uses can be modeled by the function

where t represents the number of hours the dishwasher has been running and f(t) represents the amount of energy spent in kilowatt-hours.

(a) Compute and simplify f′(t).

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(b) Suppose that an electrician wants to know how fast the dishwasher is using energy as it is turned on. Evaluate and interpret this value.