Question 1057501: 65% percent of households say they would feel secure if they had $50,000 in savings. You randomly select 8 households and ask them if they would feel secure if they had $50,000 in savings. Find the probability that the number that say they would feel secure is (a) exactly five, (b) more than five, and (c) at most five.
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! For this problem, we use the binomial probability(Pr) formula
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Pr of success is 0.65, n=8, k=5 (number of successes)
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Pr( k = 5) = 8C5 * (0.65)^5 * (1-0.65)^(8-5) where 8C5 is the combination of 8 things taken 5 at a time
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a) Pr ( k = 5 ) = 0.2785 approx 0.28
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b) Pr ( k > 5 ) = 0.4278 approx 0.43
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c) Pr ( k < or = 5 ) = 0.57
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Note for b we have to calculate Pr(k=6) + Pr(k=7) + Pr(k=8)
Note for c we have to calculate 1 - answer for b
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