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A cable TV/Internet/phone provider charges Janet \(\$ 90\) per month for all three services. In addition, Janet's monthly bill for cell phone calls and text messages averages \(\$ 77\) per month. a. What does Janet pay annually for these services? b. What is her average cost per day for these services? Round to the nearest cent.

A certain appliance requires 225 watts when it is switched on. How much would it cost to run for \(m\) minutes, at a cost of \(d\) dollars per kilowatt-hour? Express your answer algebraically.

Jessica’s parents are always telling her to turn off the lights when she leaves a room. A light bulb requires 75 watts to run when it is turned on. The fi xture in Jessica’s room requires four of these bulbs. a. Jessica’s parents estimate that she leaves the lights on unnecessarily for 2.5 hours per day. How many watt-hours of electricity are used by these bulbs during 2.5 hours? b. Approximately how many kilowatt-hours of electricity are used in a year to keep these bulbs lit for 2.5 hours per day? c. At a cost of \(\$ 0.09\) per kilowatt-hour, how much money is wasted per year by keeping these lights on unnecessarily? Round to the nearest dollar. d. If five million teenagers keep lights on as Jessica does, how much is wasted in unnecessary electric expenses?

Throughout this lesson you have used the greatest integer function \(y=[x] .\) Use your graphing calculator to view the graph of this function and find the \(y\) -coordinate for each of the following \(x\) -values. a. 2.3 b. 2.99 c. 3 d. 3.01 e. 3.99

Last year, the Forrester family spent \(\$ 1,882.56\) for electricity. They are opting to use balanced billing for next year. a. What will their monthly payment be under balanced billing? b. Last year, they had their highest bill in the summer, for \(\$ 405.67\) . Their lowest bill was in the winter. Explain why their lowest bill could not be \(\$ 178 .\)

Under his household expense budget category, Mark has allocated \(\$ 60\) per month for pet food. He can purchase wet food in a can for \(\$ 1.50\) per can or dry food in a bag for \(\$ 3\) per bag. a. Determine a budget line equation for this situation. b. Graph the budget line that will depict the different combinations of cans and bags that Mark can purchase while still remaining within his budget. c. Name a combination of bags and cans that will allow him to d. Name a combination of bags and cans that will keep him under budget. e. Name a combination of bags and cans that will cause him to be over budget.

A certain appliance uses \(w\) watts to run. If you run it for \(m\) minutes, and the cost per kilowatt-hour is \(c,\) the cost of running the appliance for \(m\) minutes is given by the formula $$\frac{w\left(\frac{m}{60}\right)}{1,000}(c)$$ Find the cost of running an appliance that requires 500 watts for 25 minutes at a cost of \(\$ 0.125\) per kWh. Round to the nearest cent.

A large appliance such as a water heater is only running when it has clicked on and is actually heating water. The time your water heater is on varies according to how much you do laundry, take showers, or run the dishwasher. The national average is 3 hours per day. a. If a water heater uses 4,200 watts, fi nd the daily cost of running it at a cost of \(0.11 per kilowatt-hour. Round to the nearest ten cents. b. Find the annual cost of running the water heater to the nearest ten dollars. c. A certain energy-saving water heater sells for \)\$ 1,100 .\( It will save 36\)\%$ in energy costs per year compared to the water heater from parts a and b. What will be the approximate annual cost of running this water heater? Round to the nearest ten dollars. d. In how many years will the new water heater "pay for itself"?

In September 1997 , the average cost for 1 gallon of home heating oil in New York City was \(\$ 1.192\) per gallon. By September 2008 , it had risen to \(\$ 4.173\) per gallon. What was the percent increase in those 11 years? Round to the nearest percent.

Air conditioners are rated by BTUs. You learned about BTUs in Lesson 8-2, Example 6. One watt-hour is equivalent to 3.413 BTUs per hour. a. How many BTUs per hour are equivalent to a kilowatt-hour? b. If an air conditioner is rated at 16,000 BTUs, how many watts does it require per hour? Round to the nearest 100 watts. c. Express your answer to part b in kilowatt-hours. d. If you run an air conditioner for 18 hours per day for 31 days in July, how many kilowatt-hours will it require for the month? Round to the nearest 100 kilowatt-hours. e. Based on your answer to part d, and a rate of \(\$ 0.13\) per kilowatt-hour, estimate the cost of running the air conditioner for July to the nearest 10 dollars.