Five percent of the welds done by the welding robots at Arbitron-Lewisburg Manufacturing are substandard and need

Question:

Five percent of the welds done by the welding robots at Arbitron-Lewisburg Manufacturing are substandard and need to be redone. Suppose you randomly choose fve recent welds. Use the binomial function to compute the probability that
a. Exactly three of the five welds are substandard.
b. None of the welds is substandard.
c. No more than two of the welds are substandard.