SOLUTION: 40% percent of households say they would feel secure if they had​ $50,000 in savings. You randomly select 88 households and ask them if they would feel secure if they had&#8

Algebra ->  Probability-and-statistics -> SOLUTION: 40% percent of households say they would feel secure if they had​ $50,000 in savings. You randomly select 88 households and ask them if they would feel secure if they had&#8      Log On


   

Question 1051630: 40% percent of households say they would feel secure if they had​ $50,000 in savings. You randomly select 88 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 Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
exactly 5 is 88C5(0.4)^5*0.6^83=1.5 X 10^(-13) or essentially 0.
4,3,2,1 will also be 0.
Therefore, c is 0.
b is 1.0
The expected value for 88 households is 88*0.4 or 35.2
The variation is 35.2*0.6 (np(1-p))=21.12, and the standard deviation is 4.6
5 households is 30.2/4.6, or 6.5 standard deviations below the mean.
Could the question be 8 households?
There the probability of 5 would be 8C50.4^5*0.6^3=0.124