Drawing a probability tree may help you.
a) There are three possible combinations:
P(Faulty, Not faulty, Not faulty)
P(Not faulty, Faulty, Not faulty)
P(Not faulty, Not faulty, Faulty)
We then use the addition rule of probability:
( \frac{3}{100} \cdot \frac{97}{100} \cdot \frac{97}{100} )...