ENVIRO SCIENCE
posted by RAYMOND .
1.Between 1950 and 2004, the world population increased exponentially from 2.5 billion to 6.4 billion, what is the percent change?
2.Calculate the percent decrease if there are 620 incoming freshmen and 500 graduated seniors?
percent change: (amount change/initial value ) x 100
I keep on getting 156% and 24% is it right?

1) correct
2) no. the initial value is 620 
So it is 156% increase and 19.4% decrease?

I agree with 156%.
Try # 2 again.
The amount of the change was 120. The initial value was 620. 
So #2 is 19.4% decrease?

Yes  it was a 19.4% decrease.