1. The problem statement, all variables and given/known data Suppose a book of 600 pages contains a total of 240 typographical errors. Develop a poisson approximation for the probability that three partiular successive pages are error-free. 3. The attempt at a solution I say that the number of errors is poissondistributed with errorate 240/600=0.4 errors/pages. The probability of 0 errors for 3 pages is: (3*0.4)^0*e^(-3*0.4)/0!=e^(-1.2) But the answer index says that the answer is e^(-12). That is, there should not be a dot there, why?