Model the situation as before: the difficulty, d, of the trick to be attempted is chosen as a number from 0 to 1.
The attempt, a, is a randomly chosen from the uniform distribution (0,1)
If a<d the trick fails and scores 0.
If a>d the trick is successful and scores a*d.
Now suppose our competitor is going for the gold and has one final attempt to beat the current highest score of 0.6
What difficulty should be attempted to maximize the chance of winning?