Question 469896
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Hi,
Note: The probability of x successes in n trials is: 
P = nCx* {{{p^x*q^(n-x)}}} where p and q are the probabilities of success and failure respectively. 
In this case p = .72 & q =.28
nCx = {{{n!/(x!(n-x)!)}}}
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