Answer
$0.068I_o $
Work Step by Step
Let the initial intensity be $I_o$.
The initial light is unpolarized, so the intensity after the first polarizer, $I_1$, will be half the initial intensity.
$$I_1=\frac{1}{2}I_o$$
Use equation 24–5 to see what happens next.
$$I_2=I_1cos^2\theta$$
We see that the next 5 sheets each reduce the intensity by a factor of $ cos^2 35^{\circ}$.
$$I_{final}=\frac{1}{2}I_o (cos^2 35^{\circ})^5=0.068I_o $$
