Please show work.

A warehouse contains 1,000 machine-made parts. A quality control worker suspects that 5% of those parts are defective. a.) Suppose the worker obtains a random sample of 30 parts (without replacement). If 5% of the parts truly are defective, then what is the probability that at least one part in this sample is defective? b.) How many parts need to be sampled in order to have 95% probability of obtaining at least one defective part