Electricity Rates in Illinois Commonwealth Edison Company supplies electricity to resident...

Electricity Rates in Illinois Commonwealth Edison Company supplies electricity to residential customers for a monthly customer charge of $11.47 plus 11 cents per kilowatt-hour for up to 600 kilowatt hours.

(a) Write a linear equation that relates the monthly charge C, in dollars, to the number x of kilowatt-hours used in a month, 0 ≤ x ≤600.

(b) Graph this equation.

(c) What is the monthly charge for using 200 kilowatthours?

(d) What is the monthly charge for using 500 kilowatthours?

(e) Interpret the slope of the line.

Source: Commonwealth Edison Company, March, 2011.