Just as money doesn’t buy happiness for individuals, the two don’t necessarily go together...

Just as money doesn’t buy happiness for individuals, the two don’t necessarily go together for countries either. However, the scatter plot does show a relationship between a country’s annual per capita income and the percentage of people in that country who call themselves “happy.”

Source: Richard Layard, Happiness: Lessons from a New Science, Penguin, 2005

Draw a line that fits the data so that the spread of the data points around the line is as small as possible. Use the coordinates of two points along your line to write the slope-intercept form of its equation. Express the equation in function notation and use the linear function to make a prediction about national happiness based on per capita income.