what is the IRR

Initial investment 350K

Incremental cash flow Discounted Cash flow 20% Disc Cash flow 20%
Year 1 50 0.833 41.65
Year 2 110 0.694 76.34
Year 3 130 0.579 75.27
Year 4 150 0.482 72.3
Year 5 100 0.402 40.2
NPV 48 (10%) 41.24

What is the IRR?
The answer is 15.4%. (10 + (48/(48+41.24) x 10)

However, I am not able to get 41.24. (instead I get 44.24), can please assist to explain how 41.24 is derived.

Thank you.