SOLUTION: It was found that 90% of American victims of health care fraud are senior citizens. If 7 victims are randomly selected,find the probility that exactly 4 are senior citizens. Round

Algebra ->  Probability-and-statistics -> SOLUTION: It was found that 90% of American victims of health care fraud are senior citizens. If 7 victims are randomly selected,find the probility that exactly 4 are senior citizens. Round       Log On


   



Question 376715: It was found that 90% of American victims of health care fraud are senior citizens. If 7 victims are randomly selected,find the probility that exactly 4 are senior citizens. Round your final answer to three decimal places.
Found 2 solutions by ewatrrr, kkrmaxwell:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi,
Note: The probability of x successes in n trials is:
P = nCx* p%5Ex%2Aq%5E%28n-x%29 where p and q are the probabilities of success and failure respectively.
In this case p=.9 and q = .1
nCx = n%21%2F%28x%21%28n-x%21%29%29 7C4 = 35
P(exactly 4 out of 7 selected are seniors) = 35*(.9)^4 *(.1)^3

Answer by kkrmaxwell(1) About Me  (Show Source):