Question

From a batch in which 20 parts are without defects and 4 - with defects, 4 parts are taken at random. What is the probability that: 1) all 4 parts without defects 2) 3 without defects and 1 part with defects 3) at least 2 - with defects

Answer 1

20+4=24=12=6=3

therefore the answer is three defect