Here is a problem that I found in a library book. In Canada, 38% of all students have an iPod. What is the probability that 10 out of 20 randomly selected students have AT LEAST ONE iPod? This is my CORRECT solution. It is a binomial distribution. So, I do P(having an iPod) = 0.38 which is the success 20 choose 10 times (.38)^10 times (.62)^10 = 0.097 I happened to come up with the correct solution after my first attempt. In my first attempt, this is what I did. P(at least one iPod) = 1 - P(no iPod) which gives the wrong answer. Why is my first attempt wrong? Please explain.