Possibly a Combination Problem

[Jason76]

You have to kill three of four dragons A, B, C and D dragons in a row before you get to be with your true love (TL). The chances that you kill them are respectively 0.4, 0.6, 0.8 and 0.9. In what order should you fight them so as to maximize your chances of being with TL?

Any ideas?

[Guest]

D -> C -> B