An article that appeared in USA Today (Septem ber 3, 2003) included a graph similar to the one shown here summarizing responses from polls conducted in 1978, 1991, and 2003 in which a sample of American adults were asked whether or not it was a good time or a bad time to buy a house.
a. Construct a time-series plot that shows how the percentage that thought it was a good time to buy a house has changed over time.
b. Add a new line to the plot from Part (a) showing the percentage that thought it was a bad time to buy a house over time. Be sure to label the lines clearly.
c. Which graph, the given bar chart or the time-series plot, best shows the trend over time?

Mar-78 Mar-91 Jun-03 Sep-03 90% 80% 70% 60% , 53% 50% 40% 30% 20% 10% 78% 78% 67% 29% 25% 19% 20% 0% Good time Bad time