- #1
2sin54
- 109
- 1
Homework Statement
There are 10 000 000 people who are going to vote. 5 500 000 will vote for the party A, the rest will vote for the party B.
20 000 voters are randomly chosen. What is the probability that there will be more party B voters than there will be party A voters (sorry for poor translation).
2. The attempt at a solution
P(party A voter) = 0.55
P(party B voter) = 0.45
There have to be at least 10 001 party B voters for the condition to be satisfied. This number can range from 10 001 to 20 000. Then, according to de Moivre-Laplace theorem the probability which I need to find:
P = Θ(λ2) - Θ(λ1) ,
where λ1 = (10 001 - 20 000*0.45)/√(20 000*0.45*(1-0.45))
Unfortunately, λ1 ≈ 14.23. λ2 is even bigger. Both, when put under the Θ function asymptotically approximate to 1. Do I have to use a different approach here?