1. Make a scatter plot of years and CO₂ concentrations. Use Excel to find the (linear) trendline and R^2, then find R by taking the square root of R^2. Write a sentence that explains the slope of the trendline ("For every additional year that passes, CO₂ concentration ..."). Is this a strong correlation?
2. Make a scatter plot of year and Global temperature. Use Excel to find the (linear) trendline and R², then find R by taking the square root of R². Write a sentence that explains the slope of the trendline. Is this a strong correlation?
3. Make a scatter plot of Carbon Dioxide concentrations and global atmospheric temperature. Use Excel to find the linear trendline and R², then find R. Write a sentence that explains the slope of the trendline. Is this a strong correlation?

   Make sure that you format all of these graphs carefully and that your trendlines are clearly labeled.

4. Use your trendlines for parts a and b to predict the global temperature and the CO₂ concentrations in the year 2010.
5. There is currently a very active debate about global warming, and some groups use these data to argue that global warming is already happening. Find two different opinions on this and summarize them. One should be claiming that global warming is taking place and that there will be significant consequences; the other should take the position that global warming is not a problem or is not happening. See if you can find arguments that actually cite data.

1. Which countries have the highest and lowest life expectancy at birth (if you are not sure what life expectancy means, look it up!) Which countries have the highest and lowest number of people per television set?
2. Make a scatter plot of the data and find the trendline and R-value. Write a sentence that explains the slope of the trendline.
3. Does a low number of people per television set cause high life expectancy? Would people in countries with low life expectancy live longer if we sent them shiploads of television sets?
4. Does a high life expectancy cause there to be fewer people per television set? If we improved the life expectancy in a country by providing better medical care would that cause there to be fewer people per television set?
5. What else could be going on here? Why might high life expectancy be strongly correlated with a low ratio of people per tv set?

1. Use the spreadsheet to estimate how long would it take (that is, how many years) to double a $1000 investment that earned 7% interest annually? How long would it take to double a $2000 investment at this interest rate? What about a $3000 investment?
2. Do you see a pattern? Could you use this work to estimate how long it would take any initial investment to double when it earns 7% annually?
3. How long would it take to double an investment earning 3.5% interest annually? 14% annually? Can you see a pattern in the answers to this question and the last one?

Buy our new model today! Make a $10,000 downpayment and pay only $100 per month for 2 years.

I kept looking and found another dealer, selling the same car, who offered:

Buy our new model today! Pay $5000 down, make a monthly payment of $50 for thefirst month, then add $50 to your payment for each additional month that you own the car. After 2 years, the car is yours.

Give me $1.00 today and take the car home! Pay 1 penny for the first month. After that, double your payment each month. After 2 years, the car is yours.

1. Before you do any calculating, which deal appears to be the best one? Explain your thinking.
2. What would your monthly payment be in the 2nd month if you take the first dealer's offer? The 10th month?
3. What would your monthly payment be in the 2nd month if you take the second dealer's offer? The 10th month?
4. What would your monthly payment be in the 2nd month if you take the third dealer's offer? The 10th month?
5. For each dealer, write an algebraic expression that gives the monthly payment.
6. Use Excel to calculate what your total payments would be for the 24 months. You can start with linearExponential.xls or build your own spreadsheet from scratch. Set up 4 columns as follows

   	 ---------- payment -----------
     Month  Dealer 1   Dealer 2   Dealer 3
       0	   10,000      5,000       1.00
       1         100         50       0.01
       2
       ...
      24
     total:
   

   Then tell Excel how to fill in the columns to 24 months. Finally, use the SUM function to add up the payments. Format your spreadsheet so that the data fit on one page and then print it to include with your homework.
7. Using what your calculations tell you to compare the three deals. Which is best? Which worst?