I need some help in the next example, as it could be in the exam next week.
Description: We are collecting seashells at the beach, and we find that out of 300 seashells 4 are nautilus. What's the probability that from the next 100 seashells we pick up 2 are nautilus?
Okay, so lambda is 4/300, but I'm not sure how to deal with the 100 situation. 100 is 1/3 of 300 so do I just divide lambda by 1/3 ?
This is not a problem about Poisson distribution.
We are asking about how many event of success out of $100$ trials.
This is a Binomial distribution where $n=100$ and $p = \frac{4}{300}$.