How much energy is required for wattage.

If a customer replaces a 85 watt bulb with an 20 watt compact fluorescent bulb that lasts 5000 hours, how much less coal (lbs)will be used to generate the electricity that is saved? Assume the electricity is generated with 30% efficiency and the energy content of the coal is 30 kJ/g.

Figures relating to cigarette smoking and cancer

Consider the following approximate figures relating to cigarette smoking and cancer. The death rate in the US population of 260 million is 12 deaths per 1000 persons per year. One-fifth of these deaths are from cancer and one-fourth of the cancer deaths are from lung cancer. Ninety percent of the lung cancer deaths occur among the sixty million people who smoke. How many deaths are there per year in the US from all causes? How many cancer deaths? How many lung cancer deaths? What is the lung cancer death rate among smokers expressed in deaths/yr/1000 smokers? What is the same rate among non-smokers?

An acre of corn can produce about 375 gallons of ethanol, using only the kernel of the corn for conversion to ethanol.

(a) An acre of corn can produce about 375 gallons of ethanol, using only the kernel of the corn for conversion to ethanol. Assume the energy input to produce an acre of corn is 15000000 kJ. If a gallon of ethanol has an embodied energy in the ethanol of about 80000 kJ, calculate the ratio of embodied energy in the ethanol to the energy required to produce the corn. (b) Assume the yield of corn stover (cobs, stalks, leaves) is 4.0 dry metric tons per acre. The extra energy required to convert the stover to ethanol is 15000 kJ/gallon; and one dry ton of stover can produce 75 gallons of ethanol. Assuming only 30% of the stover is removed for conversion to ethanol, what would be the new ene... click for more

[S02 ppm]

Calculate the concentration of SO2(ppm) that must be reached in polluted air (in ppm) if the dissolved gas is to produce a pH of 3.8 in raindrops without any oxidation of the gas. Hint: Sulfurous acid equilibria

Carbon Dating

My question is that I don't know how to set up the problem to solve it with the equation to use. C-14 activity of the youngest mammoths was measured at 1.5 disintegrations per minute gram of carbon. How many years ago did the Siberian mammoths become extinct?