7. In a free-throw test, a person only needs to make 3 shots to pass and does not need to continue shooting, but each person can shoot at most 5 times. The probability that a player with a shooting accuracy of $\frac{2}{3}$ passes the test is . $\qquad$
7. $\frac{64}{81}$.

Analysis: 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 $\frac{2}{3} \times\left(\frac{2}{3}\right)^{2} \times \frac{1}{3} \mathrm{C}_{3}^{2}=$ $\frac{8}{27}$; 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 $\frac{8}{27}+\frac{8}{27}+\frac{16}{81}=$ $\frac{64}{81}$.