The graph above shows the percent of school-age children in the United States who received immunization for various illnesses beetween 1996 and 2012. What was the average rate of increase in the percent of children immunized per year over the given time period ?

Options

A. 5 percent per year
B. 10 percent per year
C. 25 percent per year
D. 70 percent per year

Answer

A

Explanation

The question asks for a rate of change, which means you'll need the slope of the line of best fit. Pick a pair of points to use in the slope formula, such as (1998,20) and (2012,90):
`m=(y_(2)-y_(1))/(x_(2)-x_(1))=(90-20)/(2012-1998)=(70)/(14)=5`
Choice (A) is correct.