Answer:
I₃/Io % = 0.8.59
Explanation:
A polarizer is a complaint sheet for light in the polarization direction and blocks the perpendicular one. When we use two polarizers the transmission between them is described by Malus's law
I = I₀ cos² θ
Let's apply the previous exposures in our case, the light is indicatively not polarized, so the first polarized lets half of the light pass
I₁ = ½ I₀
The light transmitted by the second polarizer
I₂ = I₁ cos² θ
I₂ = (½ I₀) cos2 28
The transmission by the polarizing third is
I₃ = I₂ cos² θ₃
The angle of the third polarizer with respect to the second is
θ₃ = 90-28
θ₃ = 62º
I₃ = (½ I₀ cos² 28 cos² 62)
Let's calculate
I₃ = Io ½ 0.7796 0.2204
I₃ = Io 0.0859
I₃/Io= 0.0859 100
I₃/Io % = 0.8.59