line is tested with average of three flaws per kilometer.

a) find probability that exactly 2 flaws found.

i got 0.61 as an answers but others got .224 not sure what i did wrong.

b) how do i calculate the formula if i am testing 3 kilometers not just one?

i assume i put 9 as lambda and three for x however when i do the calculation for f(0) i get 1.234x10 to the negative 4?