This is a long shot but hey worth a try if anyone can help.

I need to work out the monthly money weighted return on a portfolio. (IRR)

Cash Flows at beginning of period ( 3 months 3 Cash flows)

Openning value 100
CF1 : 10
CF2 : 50
CF3 : 20

I have been given this formula
(OV + CF1) × (1 + R)3 + CF2 ×(1 + R)2 + CF3 × (1 + R) = CV
110 × (1 + R)3 + 50 × (1 + R)2 + 20 × (1 + R) = 186.10

Now I have a fin calculator to work out the monthly IRR however I'm not coming up with what the answer should be.

Anyone come across this and could help me out?
Cheers
4be