Hi
Note: The probability of x successes in n trials is:
P = nCx*where p and q are the probabilities of success and failure respectively.
In this case p(defective) = 5/80 =.0625 and q = .9375
nCx =
randomly take three light bulbs from the box
P(none are defective) = (.9375)^3 = .824
P(at least one is defective) = 1 - P(none are defective) = 1 -.824 = .176