Answer:
a
The probability that the selected joint was judged to be defective by neither of the two inspectors is 
b
The probability that the selected joint was judged to be defective by inspector B but not by inspector A is 
Step-by-step explanation:
From the question we are told that
The sample size is 
The number of outcome for inspector A is 
The number of outcome for inspector B is 
The number of joints judged defective by both inspector is 
The the probability that the selected joint was judged to be defective by neither of the two inspectors is mathematically represented as

Now

substituting values

So


the probability that the selected joint was judged to be defective by inspector B but not by inspector A is mathematically represented as

Now

substituting values

So


The first term(a1) is 3
The second term (a2) is obtained by multiplying 3*(-5)
The third term A3 by multiplying 3 * -5 -5 = a2 times -5
Than you go on and one with that
But your answer is
A1=3;an+1=an(-5)
40,023,032 = 40,000,000 + 20,000 + 3,000 + 30 + 2