Question 1153164: 27% of a certain country's voters think that it is too easy to vote in their country. You randomly select 12 likely voters. Find the probability that the number of likely voters who think that it is too easy to vote is (a) exactly three, (b) at least four, (c) less than eight.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! This is a binomial with n=12 p=0.27
for exactly 3, it is 12C3*0.27^3*0.73^9=0.2549
at least 4, find 0,1,2
0 is .73^12=0.0229
1 is 12*.27*.73^11=0.1016
2 is 66*.27^2*.73^10=0.2068
The sum of 0,1,2,3 [probabilities above is 0.5862
So at least 4 is 1-0.5862 or 0.4138
for 8: prob =0.0040
for 9: prob=0.0007
for 10: prob=0.00007 or 0.0001
11 and 12 are too small to consider
probability 8 or more is 0.0048
probability fewer than 8 is the complement or 0.9592
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