A 100-ml syringe piston has been set up in a science classroom so that the downward force on it can be changed by piling on textbooks and the volume of the air trapped in the syringe can be measured.

The table shows the values the students obtained as they put more books on the syringe.

1. Plot these data on a graph, with volume on the vertical axis and number of books on the horizontal axis.
2. What relationship (i.e., function) between the two variables is demonstrated by this information?
3. How could you change the data so that a direct proportionality exists between two variables related to these quantities?
4. Create a table of your new data, and draw a graph to show the proportionality.
5. Which of your two graphs makes it easier to predict the volume if six books were used? Explain why.
6. Is the relation not valid if points do not fall exactly on your line? How could you calculate a value for the uncertainty or measure of agreement? Show the calculation.