Question 972169: In a certain large city 50% of the eligible voters actually voted in the last election. If 5 eligible voters are selected at random, what is the probability that at least 2 of them voted in the last election? Assume that the population of the city is so large that the probability of voting is 1/2 for each eligible voter selected.
I only know how to barely start out the problem as I know we choose 5 random people but when it comes to the 1/2 I get very confused!
Please help and show work, the answers are: 1/2, 25/32, 13/16, 17/32, 5/8, or none.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! With at least 2, do the probability of 0 or 1 and subtract from 1. It is easier to find what you DON'T want and subtract it from 1.
P(0)= (1/2)^5
P(1)=5 different ways the 1 who voted may be chosen *(1/2)^4 * (1/2)
The first is (1/32). The second is 5/32. That is 6/32. Subtract from 1 and you get 26/32=13/16.
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