A certain kind of sheet metal has an average of 9 defects per 18 fts. Assuming a Poisson distribution, we will want to find the probability that a 36 ft piece of sheet metal has at least 12 defects. (a) First find the mean number of defects per 36 ft of this sheet metal. Give your answer as a fraction 3 defects with no units (for example, if you find the mean to be 4 then you would type "3/4" in the 36 ft answer box). defects 36 ft (b) Then find the probability that a 36 ft piece of this sheet metal has at least 12 defects. Round this answer to 4 places after the decimal point, if necessary. P(at least 12 defects)