How to determine if a probability problem has a binomial distribution or not? I'm studying for my Stats midterm and I am confused about the binomial distribution concept.
Among these 2 problems, why does the second question have a binomial distribution and not the first question?
1) In a large 2 lb bag of candies, 15% of the candies are green. The chances of pulling out at least one green candy in three tries is...
2) An owner suspects that only 5% of the customers buy a magazine and thinks that he might be able to use the display space to sell something more profitable. What is the probability that exactly 2 of the first 10 customers buy magazines?  
We already know about SPIN: S(Success/Failure) P(Probability) I(Independent) N(Fixed number of trials) and I'm curious as to why SPIN doesn't apply to the first problem as well?
Any help would be appreciated. Thank you.

From the wording of the first situation, it sounds like you are not replacing the candy after you pull it out.  Therefore you are not repeating the same fixed experiment three times in a row; rather, you are changing the experiment (and the associated probability of success) with each pick.
