Answer:
The high school graduating class changed by approximately 23%
Explanation:
we have
The high school graduating class of 2010 was 260 people
Five years later the high school graduating class was 320 people.
we know that
260 people represent the 100%
so
The difference is (320-260)=60 people
using proportion
Find out what percentage represent 60 people
Let
x ----> the percentage that represent 60 people

therefore
The high school graduating class changed by approximately 23%