A utility company charges its residential customers a flat fee for electricity plus 8 cents for each kilowatt-hour (kWh) of electricity used. Last month, a customer used 400 kWh of electricity, and he

A utility company charges its residential customers a flat fee for electricity plus 8 cents for each kilowatt-hour (kWh) of electricity used. Last month, a customer used 400 kWh of electricity, and her total bill was $35. Notice that the bill is in units of dollars and the cost per kWh is given in cents. What do you need to do to account for that?

  1. Write an equation of the line that describes the relationship between the customer’s monthly bill (call it y) and the amount of electricity used (call it x).
  2. What does the slope of this line mean?
  3. What does the intercept mean?
  4. The following month, the customer used 550 kWh of electricity. Using the linear equation from # 1 above, find out how much her bill will be.

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