Answer :

56.79%. that is the answer to your question.
AL2006

Well, it seems tome that if he makes  91%  of all his free throws, then every time
he steps up to the line, there's a  91%  chance that he'll make THAT throw.

Now the basketball has no memory, so the probability is the same for each
attempt, and the probability of succeeding on two consecutive attempts is
91%  of the probability of succeeding on the first one, and so on and so forth.

So the probability of  6  consecutive baskets is (91%) x (91%) x ... etc, 6 times.

That's just  (0.91)⁶ = 56.787 percent.