Question 414068
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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= .08 and q = .92
nCx = {{{n!/(x!(n-x)!)}}}
A. P[exactly 3 defective pens] = .2188    |Good work
B. P[at most 3 defective pens] = .7842    |Good work
C. P[no defective pens] = (.92)^30 = .082
D. Determine mean and variance 
    mean = np = 30*.08 = 2.4
 variance = npq = 30*.08*.92 = 2.208