Answer
(a) The z component is zero.
(b $\vec{E}=(1.58N/C)\hat x+(0.906N/C)\hat y$)
Work Step by Step
(a) As E is perpendicular to the direction of propagation, the z component must be zero.
(b) We can determine $\vec{E}$ in terms of unit vectors as
$\vec{E}=c(-B_y\space\hat x+B_z \space \hat y)$
We plug in the known values to obtain:
$\vec{E}=(3.00\times 10^8)(-(-5.28\times 10^8)\hat x+(3.02\times 10^{-9})\hat y)$
$\vec{E}=(1.58N/C)\hat x+(0.906N/C)\hat y$
