3a)

$\sum _{i=66}^{100}(\genfrac{}{}{0ex}{}{100}{i})\ast 0,7^i\ast 0,3^{100-i}=0.8371$
$\sum _{i=0}^{130}(\genfrac{}{}{0ex}{}{200}{i})\ast 0,7^i\ast 0,3^{200-i}=0.0728$

4a)

$0.5\ast 0.5=0.25$

b)