Answer
$P = 6.76\times 10^{-10}~W$
Work Step by Step
We can find the average power in each tube:
$P = I~A$
$P = \frac{1}{2}\rho~v~\omega^2~s_m^2~\pi~r^2$
$P = (\frac{1}{2})(1.21~kg/m^3)(343~m/s)~(3000~rad/s)^2~(12.0\times 10^{-9}~m)^2~(\pi)~(2.00\times 10^{-2}~m)^2$
$P = 3.38\times 10^{-10}~W$
We can find the total of the average power in both tubes:
$P = (2)(3.38\times 10^{-10}~W) = 6.76\times 10^{-10}~W$