Question 1207908: A report in the Child Trends DataBase indicated that, in 1996, 22.2% of twelfth grade students reported daily use of cigarettes. In 2006, 12.2% of twelfth grade students reported daily use of cigarettes.
(a) Write a linear equation that relates the percent y of twelfth grade students who smoke cigarettes daily to the number x of years after 1996.
NOTE: I think the two points needed for this problem are (1996, 0.222) and
(2006, 0.122)
I can then find the slope and use the point-slope formula to find my equation.
Am I right?
(b) Find the intercepts of the graph of your equation.
(c)Do the intercepts have any meaningful interpretation?
(d) Use your equation to predict the percentage for the year 2016. Is this result reasonable?
Answer by ikleyn(52778)   (Show Source):
You can put this solution on YOUR website! .
If you read the problem attentively, you will see these words "the number x of years after 1996" there.
These words mean that you should write 0 for 1996 and 10 for 2006.
After that, you can continue your solution in the formal way.
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The problem can be easily solved mentally without using complicated interpolation-extrapolation formula.
From the problem, the time interval is 10 years; the difference in percentage is 22.2-12.2 = 10 percents total.
It tells us that the average decreasing rate is 1 percent per year.
So we write y = 22.2 - x for percents, where x represents years after 1996 to 2006.
And it is all what we need. We get the results by the simplest way.
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