Let a random variable

$\mathrm{np}=8$

$\mathrm{npq}=4$

$\mathrm{q}=\frac{1}{2} \Rightarrow \mathrm{p}=\frac{1}{2}$

$\mathrm{n}=16$

$\mathrm{p}(\mathrm{x}=\mathrm{r})=16 \mathrm{C}_{\mathrm{r}}\left(\frac{1}{2}\right)^{16}$

$\mathrm{p}(\mathrm{x} \leq 2)=\frac{{ }^{16} \mathrm{C}_{0}+{ }^{16} \mathrm{C}_{1}+{ }^{16} \mathrm{C}_{2}}{2^{16}}$

$=\frac{137}{2^{16}}$