A sample of four different calculators is randomly selected from a group containing 15 that are defective and 26 that have no defects. Find the probability that at least one of the calculators is defective

Answer 1

P(no defective in 4 draws is) = 26/41 * 25/40 * 24/39 * 23/38 = 115/779
So, P(at least 1) = 1 - P(none) = 664/779