13.2 Math and the Environment

Water conservation arithmetic and its climate effect, plus household power demand and the case for putting solar panels on a home.

Contemporary Mathematics, 13.2 Math and the Environment

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7 exercises

13.2 Exercise 1

Brushing your teeth with the water running continually uses about 4 gal of water. Turning the faucet off when you are not rinsing uses less than one-fourth of a gallon of water. Considering the recommendation to brush your teeth twice a day, how much water would be saved in a week if the faucet was off when not rinsing?

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13.2 Exercise 3

Using the data in the example, how much water would be saved in a month if one-fifth of a town’s population of 15,000 turned the faucet off when brushing their teeth except when rinsing?

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13.2 Exercise 5

Using the data in the example, how much water would be saved in a year if one-fourth of the population of the state of Minnesota, which is approximately 5.6 million people, turned the faucet off when brushing their teeth except when rinsing for a year (52 weeks)?

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13.2 Exercise 7

A 48 in plasma television uses about 200 W. How many kilowatt-hours are needed to run the television in a month if the television is one for an average of 2.5 hours a day?

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13.2 Exercise 9

A medium-sized Energy Star–rated refrigerator uses about 575 W and runs for about 8 hours per day. What is the monthly (30 days) cost of running the refrigerator if the electric rate is 12 cents per kilowatt-hour?

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13.2 Exercise 11

An electric oven is labeled as 4,000 W. How much would it cost to bake a cake for 30 minutes if the electric rate is 14 cents per kilowatt-hour?

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13.2 Exercise 13

If a home uses approximately 30 kW of electricity per day, what size solar system would be needed to fuel 80% of a home’s needs for a month (30 days)?

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