Why take the ACT/SAT?
In the United States nearly all four-year, undergraduate colleges and universities require an admission test such as the SAT or ACT. What makes standardized tests unique from high school GPA and high school transcripts, is a standardized score allow colleges to fairly compare applicants (no matter how easy/hard the high school the student attends). Also, taking the SAT/ACT gives students access to scholarship opportunities.
To sum it up:
1) Receive acceptance into the college you want
2) Earn scholarships to pay for tuition fees