Answer: b. Estimates vary, but each person uses about 80 to 100 gallons of water per day. The largest use of household water is to flush the toilet. Be sure to fix leaky toilet and faucets to save water and energy.

The best ways to save energy when using the computer is to:

a) Shut if off when you're done, or at least the screen.

b) Let it go to screen saver.

c) Put it to sleep.

Answer: a and c.

True or False: Keep fluorescent lights on because turning them off and on causes them to burn out quicker and you lose their green advantage.

Answer: False. Turn off lights when you leave a room or when they aren't needed. Switching fluorescent lamps on and off shortens the life of the lamp or tube a little, but environmentally and economically it is best to shut off lights of any kind when not needed. The energy saved will exceed the increased lamp costs.

Which of these statements about curbside recycling is correct?

a) It's a waste of time because materials just end up in a landfill.

b) A city that recycles can make a million bucks.

c) It's more expensive than garbage hauling.

d) It ends up being more harmful to the environment because of all the trucking.

Answer: b. Curbside recycling was heavily subsidized when it was implemented 25 years ago. But now recycling is breaking even, and even earning money for some cities. Minneapolis, for example, made $1.55 million in 2006, after expenses, for recycling. The trick is to remember that recycling materials have value. Separating them by commodity -- paper, glass, metal -- preserves it.

Materials collected for recycling cannot go to landfills under Minnesota law.

Garbage disposal becomes more expensive and requires extensive trucking as landfills are put farther away from where collection takes place.

Which of the following can be recycled?

a) Foam peanuts

b) Eyeglasses

c) High heels, Crocs and flip-flops

d) All of the above

e) None of the above

Answer: d.

Shoes: Crocs and flips-flops can be ground up and made into an oil-absorbent material for oil-spill cleanup kits. Any shoe can be recycled; take them to:

• Goodwill Stores, www.goodwill.org/page/guest/about.

• Carver County Environmental Center, 116 Peavey Circle, Chaska, 952-361-1800.

• REI store in Bloomington (other REI locations may collect; call first).

Eyeglasses: Your local Lion's Club or eye-care store may collect these. Lenses are reground and given to people in need.

Foam packing: Pack-and-ship stores often accept foam peanuts for reuse. Or, call the Plastic Loose Fill Producers Council to find a drop-off site: 1-800-828-2214. For places to drop off foam blocks for recycling, contact the Alliance of Foam Packaging Recyclers, 1-410-451-8340, www.epspackaging.org/info.html .

Which is best for the environment, plastic or paper grocery bags?

Answer: Trick question. Neither. Reusable cloth or string bags are best.

Otherwise, it's a toss up. Whether paper or plastic, the retail bags you get -- and pay for -- when shopping require natural resources and energy to manufacture and transport. With plastic and paper, remember to use it up and wear it out. By reusing bags, you conserve resources and reduce waste. Although plastic bags weigh less and take up less landfill space than paper bags, they take longer to decompose. Wash and reuse plastic produce bags, and if you don't need a bag, say so. Some stores collect plastic bags for recycling.

What is an oxo-biodegradable bag?

a) Another name for a paper bag.

b) There's no such thing.

c) A plastic bag that degrades faster than a regular plastic.

Answer: c. Oxo-biodegradable plastics, a relatively new development, are plastic materials with additives that cause them to degrade under conditions of sunlight and/or mechanical stress.

Over the lifespan of an article of clothing, what percentage of the energy used is due to its original manufacture and distribution?

a) 5 percent

b) 25 percent

c) 50 percent

d) 75 percent

Answer: b. Twenty-five percent of the clothing item's energy use is due to manufacture and distribution. Seventy-five percent of the energy use is in the laundry room.

True or False: The world's cotton crop takes up 3 percent of the world's farmland and uses 25 percent of the world's insecticides, and 10 percent of all pesticides.

Answer: True.

The average food item on an American dinner plate has traveled how far?

a) 1,500 miles

b) 100 miles

c) 500 miles

d) 1,000 miles

Answer: a.

True or false: Driving an electric car will not reduce pollution, because most electricity is produced using fossil fuels that emit greenhouses gases and other pollutants.

Answer: False. Driving an electric car rather than a gas-powered car reduces pollution. The amount varies and cannot be completely eliminated.

True or False: Leaky ductwork makes a home less comfortable while it steals energy, thus increasing a home's carbon footprint.

Answer: True. Metal ductwork often has holes, gaps and spaces that leak air during heating and cooling and keep it from going where intended. That increases the work of furnace and air conditioner and drives up fuel and electricity use (and makes you uncomfortable). Seal the ductwork with mastic sealant or a metallic duct tape labeled as meeting the UL-181 standard. Do not use regular duct tape. Or hire a contractor to seal ducts from the inside with a fine spray of polymer. Costs vary, but average about $2,000. For more information, go to www.aeroseal.com.

True or False: It's a good idea to buy carbon offsets when you fly or drive to mitigate the effect of the carbon emissions created by the trip.

Answer: Trick question. It could be either; there's no concrete answer yet. Companies are selling increasingly more products and services (called carbon offsets) they claim can help cut heat-trapping carbon emissions linked to global warming. Whether those claims actually result in real carbon savings is a hotly contested debate, according to Consumer Reports magazine. The federal government has recently asked for studies and opinions.