Question

A computer maker receives parts from three suppliers, S1, S2, and S3. Fifty percent come
from S1, twenty percent from S2, and thirty percent from S3. Among all the parts supplied
by S1, 5% are defective. For S2 and S3, the portion of defective parts is 3% and 6%,
respectively.
(a) What portion of all the parts is defective?
(b) A customer complains that a certain part in her recently pur