The question goes like this:

On average, out of every 1000 items made by a certain factory worker, 1 item is defective. The items are inspected in batches. A large number of batches, each of n items, made by the worker are inspected.. The probability of at least one defective item in a batch of n items is greater than 0.02. Find the least value of n.

I'm not sure how to begin. Is the no. of trails n or 1000 items?

Thank you! please add explanations too if possible!