11. In a free-throw test, as long as a person makes 3 shots, they are qualified and do not need to shoot anymore. However, each person can shoot at most 5 times. The probability that a player with a shooting accuracy of $\frac{2}{3}$ qualifies in the test is $\qquad$ .
$=, 11 . \frac{64}{81}$.
The player:
The probability of making 3 out of 3 shots is $\left(\frac{2}{3}\right)^{3}=\frac{8}{27}$;
The probability of making 3 out of 4 shots is $\frac{2}{3} \times\left(\frac{2}{3}\right)^{2} \times \frac{1}{3} C_{3}^{2}=\frac{8}{27}$;
The probability of making 3 out of 5 shots is $\frac{2}{3} \times\left(\frac{2}{3}\right)^{2} \times\left(\frac{1}{3}\right)^{2} \mathrm{C}_{4}^{2}=\frac{16}{81}$.
The probability of passing the test is $\frac{8}{27}+\frac{8}{27}+\frac{16}{81}=\frac{64}{81}$.