50 pennies or other coins (all coins must be the same value)

If you do not have 50 pennies, you may cut 50 penny shaped pieces of paper and put an x on only one side of each piece of paper.

Procedure:

The coins represent a material that will decay over time. As time passes, some of the material will change from one substance to another. Each time you turn a penny over, you are representing the original (parent material) substance changing into another substance (daughter material).

1. Turn all 50 coins heads up. Imagine that 5 years have gone by.

2. Turn 25 coins tails up. You now have 50% parent material and 50% daughter material. What is the half life of this substance? (20 Points)

3. Imagine that another half life has gone by. Remember that ONLY the parent material can change to the daughter material. Turn over your pennies to represent the passing of another half life. How much total parent material and how much total daughter material do you now have? You may express your answer in number of pennies or in %. (Note: Since you cannot turn over half a penny, round the actual number of pennies you would turn over up.) (20 points)

4. How many half lives will pass before you have only 3 pennies that are parent material and 47 pennies that are daughter material? (20 Points)

Question 1: Turn 25 coins tails up. You now have 50% parent material and 50% daughter material. What is the half life of this substance? (20 Points)

Answer:

Based upon the given information, we can assume that the half life of this coin material is 5 years.

Question 2: Imagine that another half life has gone by. Remember that ONLY the parent material can change to the daughter material. Turn over your pennies to represent the passing of another half life. How much total parent material and how much total daughter material do you now have? You may express your answer in number of pennies or in %. (Note: Since you cannot turn over half a penny, round the actual number of pennies you would turn over up.) (20 points)

Answer:

Based upon the given information from Question 2 and Question 3, we can assume that 13 additional coins would be turned over. We started with 50, than flipped 50% of them over, and now another 50% over. We have 12 coins left.

Question 3: How many half lives will pass before you have only 3 pennies that are parent material and 47 pennies that are daughter material? (20 Points)

Answer:

Based upon the given information from all the questions, and based upon our answers we can assume this:

1st half-life: 50 turned to 25 coins

2nd half-life: 25 turned to 12 coins

3rd half-life: 12 turns to 6 coins

4th half-life: 6 turns to 3 coins

So, after 4 half-lives (or after 20 years) we would have 3 coins left that have parent material.

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For future reference please do not post as complex questions like this, if you do (post a question that is similar to this) please state the following information:

"All questions posted in this post relate to one-another and cannot be answered without the other questions..."