I honestly don't know if this is right but it may make sense: x is the event of picking up a rotten orange. Probability that x is more than or equal to 1 = 1 - p(x=0) so use binomialpdf on calculator where trial is 4, p = 1/12(5/60), x = 0 1 - binoomialpdf(4, 1/12, 0) and u get 0.294