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Elli N.'s Resources

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Both Edward and Barbara have approached this problem correctly. Edward's approach is for a pre-algebra/algebra level, whilst Barbara's is suitable for 4th-5th grade math problems teaching pattern recognition.

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Hi Alannah,   This problem involves calculating the difference between a positive number and a negative number. When subtracting negative numbers, it's helpful to remember this saying: "The enemy (-) of my enemy (-) is (=) my friend (+)"   In other...

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Hi Angela,   The most significant source of carbon in your compost heap will be plant material.  Think of what goes into a compost bin - food scraps, leaves, some types of paper. All of this will contain carbon, because it comes from plants.   Does that make sense...

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Carbon-14 Dating (answer)

Hi John,   The half-life for Carbon-14 is 5,730 years. This means that every 5,730 years, we halve the amount of C14 we have.   At time=0, our C14 level is 100%. At time = 5,730 years, we have 50% of the C14 left. At time = 2x5,730 we have 25% of our C14 left.   So...