SOLUTION: Use a normal approximation to find the probability of the indicated number of voters. In this case, assume that 127 eligible voters aged 18-24 are randomly selected. Suppose
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Question 1162361: Use a normal approximation to find the probability of the indicated number of voters. In this case, assume that 127 eligible voters aged 18-24 are randomly selected. Suppose a previous study showed that among eligible voters aged 18-24, 22% of them voted.
Probability that fewer than 33 voted Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! The prior mean is np=127*.22=27.94
sd is sqrt(V) and V=np(1-p)=27.94*.78=21.79
so sd is 4.67
fewer than 33, use 32.5 with continuity correction factor
z<(32.5-27.94)/4.67
z< 0.98
probability is 0.8365
Can use binomial to check the probability 32 or fewer voted, the exact value, which is 0.8360.
