Depends on what a util is. The probability of an event is a pretty well-defined concept, but what a util means to me is free-floating without something to compare it to. If one util is a slice of Wonder bread on an empty stomach for a well-nourished person, then let's go with n = 10.
Why does it matter? How exactly are you choosing n?
This problem was invented by Armok from #lesswrong. Discuss.