I would like some help with working out virus exposure risk/probability/chance in a workplace. I know nothing about stats/probability and this may be really easy but I just don’t know. What would be really useful is a formula so I can feed in different numbers and get a figure that might help with decision making.

Question

What is the probability (or is it chance) of someone in an office having the virus?

Variables

Official virus rate in a community = 50 per 100,000 people

Community size = 200,000 people

Office size = 10 people (all from this community)

More Questions:

What happens to the figure if the community virus rate doubles?

What happens to the figure if the office size doubles or if it halves?

… this may just be dividing or multiplying by 2 but is it that simple?

If the community virus rate doubles, does halving the number of people in the office keep the exposure risk the same?

Any help greatly appreciated. The last maths I did was for an O Level in the 1980's (I got a C) and I can still hear my teacher’s voice saying “pay attention, you will need this one day…”