here please:

A manufacturer's products are broken 10% of the time (on average). (a) You buy 20 pieces. Calculate the probabilities for the following events: A: exactly 5 pieces are broken B: at most 2 pieces are broken C: no pieces are broken D: at least 2, but at most 5 pieces are broken E: at least 3 pieces are broken (b) How many pieces do you have to buy, in order to have at least one broken piece with a probability of at least 99%