In a village with a population of 1500,the probability of a person falling sick is 0.002. Find the probability that

Question

a)3people fall sick in a week
b)less than 3 fall sick in a week
c)at most 3 fall sick in a week
d)more than 2 fall sick in a week

Answer 1

this is a binomial probability
... sick (.002) or not sick (.998)
... (n + s)^1500

expanding ... n^1500 + 1500 n^1499 s +
1500C2 n^1498 s^2 + 1500C3 n^1497 s^3 + ...

a) 4th term

b) sum of 1st three terms

c) sum of 1st four terms

d) 1 - [answer b)]