DO NOT COPY AND PASTE ANOTHER ANSWER FROM SOMEONE ELSES QUESTION THAT IS ALREADY POSTED

In the weekend, however, demand is usually higher. It is estimated that orders arrive every 2.5 minutes for the in-store shoppers. The time estimates are the same as in the previous questions. That is, it takes 25 minutes on average for a shopper to pick all items on the list, and 15 minutes to check out the items and move them to the staging area. The site manager hopes to have enough capacity to handle all orders. At least how many in-store shoppers are needed at the same time?

Note: 1. Do not round your intermediate numbers (in case they are not integers, you may keep them as a fractional number). However, your final answer should be a whole number (since we are deciding on the number of shoppers)