Formulate a four-state model related to Fig. 4.11, as discussed in the text, where the component states two failures and three failures are not merged but are distinct. Solve the model for the...

Formulate a four-state model related to Fig. 4.11, as discussed in the text, where the component states two failures and three failures are not merged but are distinct. Solve the model for the four-state probabilities and show that the first two states are identical with Eqs. (4.25a, b) and that the sum of the third and fourth states equals Eq. (4.25c).