Let P(n,p,k) be the probability that k customers want to buy the magazine. We know that it is a binominal distribution and P(n,p,k)=\frac{(n-k)!\,k!}{n!} p^k (1-p)^{n-k}
Now, compare the situation "x magazines printed" and "x+1 magazines printed".
- If there are not more than x potential...