Hello all. This is NOT homework. Here is the question: Approximately 10% of the population is left-handed. In a classroom of 7 people, find the probability that at least one person is left handed. Assume independence. a) 0.1000 b) 0.0823 c) 0.9176 d) 0.7000 Here is my approach to the question: Let LH: left handed and RH: right handed P(at least 1 LH) = P(not all RH) P(not all RH) = 1 - P(all RH) P(all RH) = (1 - .1)^7 = .9^7 P(not all RH) = 1 - .9^7 P(at least 1 LH) = 1 - .9^7 = .5217 As can be seen, my answer is not one of the options shown above. I have been trying to do this question for a while now and have reached the point of frustration. May someone please help? Note: Does my problem have to do with the fact that LH and RH are not mutually exclusive? In other words someone may be LH and RH? Thank you!