If 10% of all disk drives produced on an assembly line are defective, what is the probability that there will be exactly one defect in a random sample of 5 of these? What is the probability that there will be no defects in a random sample of 5?

solution:

p=ncx,. p^x. Q^{n-x}//

where p and q are the probabilities of success and failure respectively.//

in this case p = 0.10 and Q=0.90//

ncx = / frac{n!}{x! (n-x!) }//

p (exactly one defect in a random sample of 5) / /

=5 (0.10) ^1 (0.90) ^4=0.3281//

p (no. defects in a random sample of 5) / /

=1 (0.90) ^5=0.5905