Under the following assumptions, why would the MIRR and IRR forumlas provide different outcomes?

Year 0
-50,000

Year 1-5
17,500

Cost of money: 10%

MIRR= 16.4%



Year 0
-50,000
Years 1-5
12,500 (next of 10% cost of money)

IRR=7.9%


Which one is correct, which one should I use?

Ron