SOLUTION: If the probability that a student in the statistic class will score grade A in the final exams is 0.72, determine the probability that out of 5 students selected random from the cl

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Question 469896: If the probability that a student in the statistic class will score grade A in the final exams is 0.72, determine the probability that out of 5 students selected random from the class at least 2 scored grade A?
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 = .72 & q =.28

nCx = n%21%2F%28x%21%28n-x%29%21%29

5 students selected

P(at least 2 scored an A) = 1 - P(0 scoring an A) -P(1 scoring an A)

                          = 1 - (.28)^5 - 5(.72)^1(.28)^4 = .9762