I am trying to see if I am calculating correctly. Please check my calculations and advise if I am incorrect.

To help him determine if it really is worth it to get a college education John wants to see what the return on investment (ROI) will be 20 years after graduation. After some research John discovers that for his career choice he can expect to earn $1.6 million with a degree and $809,000 without one. What is Johns 20 year ROI?

John's Initial Investment for Tuition/book/lost wages is: $243,979.28 and used for this calculation:

PV	-243,979.28
N	20
PMT	39,550/yr
I/Y	15.829

John's 20 year ROI is 15.83%