A lot consists of N transistors, and of these M(M<=N) are defective. We randomly select two transistors without replacement from this lot and determine whether they are defective of nondefective. The random variable
1 if the ith transistor is nondefective,
Xi= i=1,2
0 if the ith transistor is defective,
Determine the joint probability function for X1 and X2. What are the marginal probability functions for X1 and X2? Are X1 and X2 independent random variables?