Let $X$ and $Y$ be two independent random variables with the cumulative distribution functions
\[
F_X(x) = 1 - \left(\frac{3}{4}\right)^x, \quad x = 1,2,3,\ldots
\]
\[
F_Y(y) = 1 - \left(\frac{2}{3}\right)^y, \quad y = 1,2,3,\ldots
\]
respectively. Let $Z = \min\{X, Y\}$. Then, the probability $P(Z \ge 6)$ is