Each of 1000 people in a place independently has a certain

disease with probability 0.005.

i Find the probability that at least one person has the disease

Mr F says: 1 - Pr(X = 0) = ....
ii. Find the probability that there is more than one person has the disease, if we know that there is at least one person having the disease

Mr F says: Use the conditional probablity formula on .
iii. If one of the 1000 people knows that he has the disease. What does

the probability that more than one person (including himself) has the

disease

Please help me by not just telling the answers but explaining why as I don't understand anything.

For example first question is it 1-(1-0.005)=0.995??????