Question 1047225
Probability all 5 are defective is 0.1^5=0.00001
First two defective is 0.1^2*(0.9)^3=0.00729
The probability is 0.9*0.1*0.9*0.9*0.1=0.00729
The outcomes where 2 are defective is 5C2, or 5!/3!2!, and that is 10
Therefore the probability exactly two are defective is 10*(0.1)^2*(0.9)^3=0.0729.